Update Microsoft.Extensions.AI version & expose JSON configuration on McpServerResourceCreateOptions

[sbomer]

Per #357 (comment), this should fix#357.

[eiriktsarpalis]

Is there any chance you could add a test validating that this is indeed fixed?

[stephentoub]

Updating the version is fine and good (we need to anyway for other reasons), but...

Are you sure this impacts the cited issue? Wasn't that fix in the 9.5 version already?

[sbomer]

Hmm, actually it looks like the mentioned fix was already in 9.5.0: dotnet/extensions@v9.4.0...v9.5.0.

Confirmed that updating to the latest version of ModelContextProtocol fixed the issue for me, so I think #357 is fixed already.

[stephentoub]

@eiriktsarpalis, this is failing with errors like:

Message: System.NotSupportedException : JsonTypeInfo metadata for type 'ModelContextProtocol.Protocol.PromptMessage[]' was not provided by TypeInfoResolver of type '[ModelContextProtocol.McpJsonUtilities+JsonContext, Microsoft.Extensions.AI.AIJsonUtilities+JsonContext]'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
Stack Trace: ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
JsonSchemaExporter.GetJsonSchemaAsNode(JsonSerializerOptions options, Type type, JsonSchemaExporterOptions exporterOptions)
AIJsonUtilities.CreateJsonSchemaCore(Type type, String parameterName, String description, Boolean hasDefaultValue, Object defaultValue, JsonSerializerOptions serializerOptions, AIJsonSchemaCreateOptions inferenceOptions)
AIJsonUtilities.CreateJsonSchema(Type type, String description, Boolean hasDefaultValue, Object defaultValue, JsonSerializerOptions serializerOptions, AIJsonSchemaCreateOptions inferenceOptions)
ReflectionAIFunctionDescriptor.ctor(DescriptorKey key, JsonSerializerOptions serializerOptions)
ReflectionAIFunctionDescriptor.GetOrCreate(MethodInfo method, AIFunctionFactoryOptions options)
ReflectionAIFunction.Build(MethodInfo method, Object target, AIFunctionFactoryOptions options)
AIFunctionFactory.Create(MethodInfo method, Object target, AIFunctionFactoryOptions options)
AIFunctionMcpServerPrompt.Create(MethodInfo method, Object target, McpServerPromptCreateOptions options) line 39
AIFunctionMcpServerPrompt.Create(Delegate method, McpServerPromptCreateOptions options) line 24
McpServerPrompt.Create(Delegate method, McpServerPromptCreateOptions options) line 161
McpServerPromptTests.CanReturnPromptMessages() line 212
--- End of stack trace from previous location ---

Any idea what changed in Microsoft.Extensions.AI.Abstractions that would have affected this? I'm concerned we had an unexpected fallout from something.

[stephentoub]

This is also failing:

 Message: System.InvalidOperationException : The node must be of type 'JsonObject'.
Stack Trace: ThrowHelper.ThrowInvalidOperationException_NodeWrongType(ReadOnlySpan`1 supportedTypeNames)
JsonNode.AsObject()
JsonNode.set_Item(String propertyName, JsonNode value)
<>c.<SupportsSchemaCreateOptions>b__15_2(AIJsonSchemaCreateContext context, JsonNode node) line 327
<>c__DisplayClass32_0.<CreateJsonSchemaCore>g__TransformSchemaNode|0(JsonSchemaExporterContext schemaExporterContext, JsonNode schema)
JsonSchema.<ToJsonNode>g__CompleteSchema|100_0(JsonNode schema, <>c__DisplayClass100_0&)
JsonSchema.ToJsonNode(JsonSchemaExporterOptions options)
JsonSchema.ToJsonNode(JsonSchemaExporterOptions options)
JsonSchemaExporter.GetJsonSchemaAsNode(JsonTypeInfo typeInfo, JsonSchemaExporterOptions exporterOptions)
JsonSchemaExporter.GetJsonSchemaAsNode(JsonSerializerOptions options, Type type, JsonSchemaExporterOptions exporterOptions)
AIJsonUtilities.CreateJsonSchemaCore(Type type, String parameterName, String description, Boolean hasDefaultValue, Object defaultValue, JsonSerializerOptions serializerOptions, AIJsonSchemaCreateOptions inferenceOptions)
AIJsonUtilities.CreateJsonSchema(Type type, String description, Boolean hasDefaultValue, Object defaultValue, JsonSerializerOptions serializerOptions, AIJsonSchemaCreateOptions inferenceOptions)
ReflectionAIFunctionDescriptor.ctor(DescriptorKey key, JsonSerializerOptions serializerOptions)
ReflectionAIFunctionDescriptor.GetOrCreate(MethodInfo method, AIFunctionFactoryOptions options)
ReflectionAIFunction.Build(MethodInfo method, Object target, AIFunctionFactoryOptions options)
AIFunctionFactory.Create(MethodInfo method, Object target, AIFunctionFactoryOptions options)
AIFunctionMcpServerPrompt.Create(MethodInfo method, Object target, McpServerPromptCreateOptions options) line 39
AIFunctionMcpServerPrompt.Create(Delegate method, McpServerPromptCreateOptions options) line 24
McpServerPrompt.Create(Delegate method, McpServerPromptCreateOptions options) line 161
McpServerPromptTests.SupportsSchemaCreateOptions() line 332
--- End of stack trace from previous location ---

[eiriktsarpalis]

I speculate that it's related to the output schema now being generated for every AI function. If our server infrastructure was hardcoding detection of return types PromptMessage[], then STJ was not being exercised for that particular type until today. I'll investigate further.