fix(tasks): #626 model task capabilities correctly

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },

crates/rmcp/src/model.rs

@@ -2089,6 +2089,7 @@ macro_rules! ts_union {
  (@declare_end $U:ident { $($declared:tt)* }) => {
  #[derive(Debug, Serialize, Deserialize, Clone)]
  #[serde(untagged)]
+ #[allow(clippy::large_enum_variant)]
  #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
  pub enum $U {
  $($declared)*

crates/rmcp/src/model/capabilities.rs

@@ -40,24 +40,121 @@ pub struct RootsCapabilities {
  pub list_changed: Option<bool>,
 }
 
-/// Task capability negotiation for SEP-1686.
+/// Task capabilities shared by client and server.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct TasksCapability {
- /// Map of request category (e.g. "tools.call") to a boolean indicating support.
  #[serde(skip_serializing_if = "Option::is_none")]
- pub requests: Option<TaskRequestMap>,
- /// Whether the receiver supports `tasks/list`.
+ pub requests: Option<TaskRequestsCapability>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub list: Option<bool>,
- /// Whether the receiver supports `tasks/cancel`.
+ pub list: Option<JsonObject>,
  #[serde(skip_serializing_if = "Option::is_none")]
- pub cancel: Option<bool>,
+ pub cancel: Option<JsonObject>,
 }
 
-/// A convenience alias for describing per-request task support.
-pub type TaskRequestMap = BTreeMap<String, bool>;
+/// Request types that support task-augmented execution.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskRequestsCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub sampling: Option<SamplingTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub elicitation: Option<ElicitationTaskCapability>,
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub tools: Option<ToolsTaskCapability>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct SamplingTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create_message: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ElicitationTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub create: Option<JsonObject>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct ToolsTaskCapability {
+ #[serde(skip_serializing_if = "Option::is_none")]
+ pub call: Option<JsonObject>,
+}
+
+impl TasksCapability {
+ /// Default client tasks capability with sampling and elicitation support.
+ pub fn client_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: Some(SamplingTaskCapability {
+ create_message: Some(JsonObject::new()),
+ }),
+ elicitation: Some(ElicitationTaskCapability {
+ create: Some(JsonObject::new()),
+ }),
+ tools: None,
+ }),
+ }
+ }
+
+ /// Default server tasks capability with tools/call support.
+ pub fn server_default() -> Self {
+ Self {
+ list: Some(JsonObject::new()),
+ cancel: Some(JsonObject::new()),
+ requests: Some(TaskRequestsCapability {
+ sampling: None,
+ elicitation: None,
+ tools: Some(ToolsTaskCapability {
+ call: Some(JsonObject::new()),
+ }),
+ }),
+ }
+ }
+
+ pub fn supports_list(&self) -> bool {
+ self.list.is_some()
+ }
+
+ pub fn supports_cancel(&self) -> bool {
+ self.cancel.is_some()
+ }
+
+ pub fn supports_tools_call(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.tools.as_ref())
+ .and_then(|t| t.call.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_sampling_create_message(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.sampling.as_ref())
+ .and_then(|s| s.create_message.as_ref())
+ .is_some()
+ }
+
+ pub fn supports_elicitation_create(&self) -> bool {
+ self.requests
+ .as_ref()
+ .and_then(|r| r.elicitation.as_ref())
+ .and_then(|e| e.create.as_ref())
+ .is_some()
+ }
+}
 
 /// Capability for handling elicitation requests from servers.
 ///
@@ -368,4 +465,67 @@ mod test {
  })
  );
  }
+
+ #[test]
+ fn test_task_capabilities_deserialization() {
+ // Test deserializing from the MCP spec format
+ let json = serde_json::json!({
+ "list": {},
+ "cancel": {},
+ "requests": {
+ "tools": { "call": {} }
+ }
+ });
+
+ let tasks: TasksCapability = serde_json::from_value(json).unwrap();
+ assert!(tasks.list.is_some());
+ assert!(tasks.cancel.is_some());
+ assert!(tasks.requests.is_some());
+ let requests = tasks.requests.unwrap();
+ assert!(requests.tools.is_some());
+ assert!(requests.tools.unwrap().call.is_some());
+ }
+
+ #[test]
+ fn test_tasks_capability_client_default() {
+ let tasks = TasksCapability::client_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_sampling_create_message());
+ assert!(tasks.supports_elicitation_create());
+ assert!(!tasks.supports_tools_call());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(
+ json["requests"]["sampling"]["createMessage"],
+ serde_json::json!({})
+ );
+ assert_eq!(
+ json["requests"]["elicitation"]["create"],
+ serde_json::json!({})
+ );
+ }
+
+ #[test]
+ fn test_tasks_capability_server_default() {
+ let tasks = TasksCapability::server_default();
+
+ // Verify structure
+ assert!(tasks.supports_list());
+ assert!(tasks.supports_cancel());
+ assert!(tasks.supports_tools_call());
+ assert!(!tasks.supports_sampling_create_message());
+ assert!(!tasks.supports_elicitation_create());
+
+ // Verify serialization matches expected format
+ let json = serde_json::to_value(&tasks).unwrap();
+ assert_eq!(json["list"], serde_json::json!({}));
+ assert_eq!(json["cancel"], serde_json::json!({}));
+ assert_eq!(json["requests"]["tools"]["call"], serde_json::json!({}));
+ }
 }

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -519,6 +519,18 @@
  }
  }
  },
+ "ElicitationTaskCapability": {
+ "type": "object",
+ "properties": {
+ "create": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "EmptyObject": {
  "description": "This is commonly used for representing empty objects in MCP messages.\n\nwithout returning any specific data.",
  "type": "object",
@@ -1718,6 +1730,18 @@
  "format": "const",
  "const": "notifications/roots/list_changed"
  },
+ "SamplingTaskCapability": {
+ "type": "object",
+ "properties": {
+ "createMessage": {
+ "type": [
+ "object",
+ "null"
+ ],
+ "additionalProperties": true
+ }
+ }
+ },
  "SetLevelRequestMethod": {
  "type": "string",
  "format": "const",
@@ -1774,33 +1798,81 @@
  "uri"
  ]
  },
+ "TaskRequestsCapability": {
+ "description": "Request types that support task-augmented execution.",
+ "type": "object",
+ "properties": {
+ "elicitation": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ElicitationTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "sampling": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/SamplingTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ },
+ "tools": {
+ "anyOf": [
+ {
+ "$ref": "#/definitions/ToolsTaskCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
  "TasksCapability": {
- "description": "Task capability negotiation for SEP-1686.",
+ "description": "Task capabilities shared by client and server.",
  "type": "object",
  "properties": {
  "cancel": {
- "description": "Whether the receiver supports `tasks/cancel`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "list": {
- "description": "Whether the receiver supports `tasks/list`.",
  "type": [
- "boolean",
+ "object",
  "null"
- ]
+ ],
+ "additionalProperties": true
  },
  "requests": {
- "description": "Map of request category (e.g. \"tools.call\") to a boolean indicating support.",
+ "anyOf": [
+ {
+ "$ref": "#/definitions/TaskRequestsCapability"
+ },
+ {
+ "type": "null"
+ }
+ ]
+ }
+ }
+ },
+ "ToolsTaskCapability": {
+ "type": "object",
+ "properties": {
+ "call": {
  "type": [
  "object",
  "null"
  ],
- "additionalProperties": {
- "type": "boolean"
- }
+ "additionalProperties": true
  }
  }
  },