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Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689

Closed
#1012
Closed
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
#1012
Labels
P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on

Description

@kentcdodds
kentcdodds
opened on Jun 23, 2025

Describe the bug
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.

To Reproduce
Steps to reproduce the behavior:

  1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
  2. Call the elicitInput method (for example, as part of the elicitation feature).
  3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.

Expected behavior
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.

Logs

EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

Suggestions

  • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
  • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
  • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
  • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.

Additional context

  • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
  • The relevant code in the SDK appears here: src/server/index.ts#L328
  • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
  • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.

Metadata

Metadata

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No one assigned

    Labels

    P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on

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      Milestone

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      None yet

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function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
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btn.textContent = 'Copy';
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btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
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observer.observe(document.body, { childList: true, subtree: true });
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})();
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try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
      Skip to content
      Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
      Closed
      #1012
      Closed
      Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
      #1012
      Labels
      P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
      Description
      @kentcdodds
      kentcdodds
      opened on Jun 23, 2025
      Describe the bug
      
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
      To Reproduce
      
Steps to reproduce the behavior:
      1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
      2. Call the elicitInput method (for example, as part of the elicitation feature).
      3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
      Expected behavior
      
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
      Logs
      EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

      Suggestions
      • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
      • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
      • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
      • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
      Additional context
      • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
      • The relevant code in the SDK appears here: src/server/index.ts#L328
      • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
      • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
      Metadata
      Metadata
      Assignees
      No one assigned
        Labels
        P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
        Type
        No type
        Projects
        No projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
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.markdown-body hr { border-color: #30363d; }
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document.head.appendChild(style);
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} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
          Skip to content
          Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
          Closed
          #1012
          Closed
          Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
          #1012
          Labels
          P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
          Description
          @kentcdodds
          kentcdodds
          opened on Jun 23, 2025
          Describe the bug
          
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
          To Reproduce
          
Steps to reproduce the behavior:
          1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
          2. Call the elicitInput method (for example, as part of the elicitation feature).
          3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
          Expected behavior
          
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
          Logs
          EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

          Suggestions
          • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
          • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
          • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
          • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
          Additional context
          • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
          • The relevant code in the SDK appears here: src/server/index.ts#L328
          • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
          • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
          Metadata
          Metadata
          Assignees
          No one assigned
            Labels
            P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
            Type
            No type
            Projects
            No projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
              Skip to content
              Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
              Closed
              #1012
              Closed
              Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
              #1012
              Labels
              P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
              Description
              @kentcdodds
              kentcdodds
              opened on Jun 23, 2025
              Describe the bug
              
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
              To Reproduce
              
Steps to reproduce the behavior:
              1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
              2. Call the elicitInput method (for example, as part of the elicitation feature).
              3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
              Expected behavior
              
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
              Logs
              EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

              Suggestions
              • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
              • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
              • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
              • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
              Additional context
              • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
              • The relevant code in the SDK appears here: src/server/index.ts#L328
              • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
              • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
              Metadata
              Metadata
              Assignees
              No one assigned
                Labels
                P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                Type
                No type
                Projects
                No projects
                  Milestone
                  No milestone
                  Relationships
                  None yet
                  Development
                  No branches or pull requests
                  Issue actions
                  
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
                  Skip to content
                  Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
                  Closed
                  #1012
                  Closed
                  Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
                  #1012
                  Labels
                  P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                  Description
                  @kentcdodds
                  kentcdodds
                  opened on Jun 23, 2025
                  Describe the bug
                  
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
                  To Reproduce
                  
Steps to reproduce the behavior:
                  1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
                  2. Call the elicitInput method (for example, as part of the elicitation feature).
                  3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
                  Expected behavior
                  
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
                  Logs
                  EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

                  Suggestions
                  • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
                  • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
                  • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
                  • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
                  Additional context
                  • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
                  • The relevant code in the SDK appears here: src/server/index.ts#L328
                  • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
                  • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
                  Metadata
                  Metadata
                  Assignees
                  No one assigned
                    Labels
                    P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                    Type
                    No type
                    Projects
                    No projects
                      Milestone
                      No milestone
                      Relationships
                      None yet
                      Development
                      No branches or pull requests
                      Issue actions
                      
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
                      Skip to content
                      Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
                      Closed
                      #1012
                      Closed
                      Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
                      #1012
                      Labels
                      P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                      Description
                      @kentcdodds
                      kentcdodds
                      opened on Jun 23, 2025
                      Describe the bug
                      
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
                      To Reproduce
                      
Steps to reproduce the behavior:
                      1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
                      2. Call the elicitInput method (for example, as part of the elicitation feature).
                      3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
                      Expected behavior
                      
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
                      Logs
                      EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

                      Suggestions
                      • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
                      • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
                      • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
                      • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
                      Additional context
                      • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
                      • The relevant code in the SDK appears here: src/server/index.ts#L328
                      • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
                      • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
                      Metadata
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
                          Skip to content
                          Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
                          Closed
                          #1012
                          Closed
                          Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
                          #1012
                          Labels
                          P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                          Description
                          @kentcdodds
                          kentcdodds
                          opened on Jun 23, 2025
                          Describe the bug
                          
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
                          To Reproduce
                          
Steps to reproduce the behavior:
                          1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
                          2. Call the elicitInput method (for example, as part of the elicitation feature).
                          3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
                          Expected behavior
                          
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
                          Logs
                          EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

                          Suggestions
                          • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
                          • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
                          • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
                          • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
                          Additional context
                          • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
                          • The relevant code in the SDK appears here: src/server/index.ts#L328
                          • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
                          • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) · Issue #689 · modelcontextprotocol/typescript-sdk · GitHub
                              Skip to content
                              Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed) #689
                              Closed
                              #1012
                              Closed
                              Elicitation feature fails on Cloudflare Workers due to AJV code generation (EvalError: Code generation from strings disallowed)#689
                              #1012
                              Labels
                              P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                              Description
                              @kentcdodds
                              kentcdodds
                              opened on Jun 23, 2025
                              Describe the bug
                              
When using the elicitInput (elicitation) feature in a Cloudflare Workers environment, schema validation fails with an EvalError: Code generation from strings disallowed. This is due to AJV v6 using new Function for dynamic code generation, which is not permitted in edge environments like Cloudflare Workers.
                              To Reproduce
                              
Steps to reproduce the behavior:
                              1. Use the @modelcontextprotocol/sdk in a Cloudflare Workers environment.
                              2. Call the elicitInput method (for example, as part of the elicitation feature).
                              3. Observe that schema validation fails with an EvalError after submitting a response to the elicitation request.
                              Expected behavior
                              
Schema validation should work in edge environments like Cloudflare Workers, which do not allow dynamic code generation (e.g., new Function). The SDK should use a compatible JSON Schema validator or provide a way to inject one.
                              Logs
                              EvalError: Code generation from strings disallowed for this context
at new Function (<anonymous>)
at Ajv3.localCompile (.../index.js:3411:30)
at Ajv3.resolve (.../index.js:2571:73)
at Object.resolveRef (.../index.js:3475:26)
at Object.generate_ref [as code] (.../index.js:3808:26)
at Object.generate_validate [as validate] (.../index.js:3128:40)
at Object.generate_properties [as code] (.../index.js:5825:30)
at generate_validate (.../index.js:3220:39)
at localCompile (.../index.js:3384:26)
at Ajv3.compile (.../index.js:3356:17)

                              Suggestions
                              • Consider replacing AJV v6 with a JSON Schema validator that is compatible with edge environments, such as @cfworker/json-schema.
                              • Alternatively, upgrade to AJV v8 and use its interpreted mode (code: { source: false }), which does not rely on dynamic code generation.
                              • Provide a configuration option or hook in the SDK to allow users to supply their own schema validator, making the SDK more flexible for different environments.
                              • Document any current limitations or workarounds for using the SDK in edge environments like Cloudflare Workers.
                              Additional context
                              • This is a blocker for using the elicitation feature on Cloudflare Workers and other edge environments.
                              • The relevant code in the SDK appears here: src/server/index.ts#L328
                              • My use case is using the elicitation feature for user input in a journaling app deployed on Cloudflare Workers.
                              • AJV v6 is not compatible with edge environments due to its reliance on dynamic code generation. Consider using a validator like @cfworker/json-schema or upgrading to AJV v8 with interpreted mode.
                              Metadata
                              Metadata
                              Assignees
                              No one assigned
                                Labels
                                P1Significant bug affecting many users, highly requested featurebugSomething isn't workingready for workEnough information for someone to start working on
                                Type
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                                Projects
                                No projects
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                                  No milestone
                                  Relationships
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                                  Issue actions