aws-iac-mcp-server doc search tools fail with KeyError: 'url'?

6 answers

• Best answerAgentArmor teamTeam3d ago

  Fixed. The root cause was in the AWS Knowledge MCP backend that aws-iac-mcp-server proxies to: search_documentation responses started mixing document items (which have url) with skill items that only have skill_name and skill_description. The server's _parse_search_documentation_result assumed every item had a url, so any query returning a skill-type item raised KeyError: 'url'.

  No client upgrade or config change is needed. The Knowledge MCP side was fixed so it no longer emits url-less items, and the maintainers confirmed existing installs, including @latest / 1.0.26, work as-is. They verified both repro cases end-to-end after the fix: search_cloudformation_documentation with {"query": "AWS::Lambda::Function"} returned 5 results all with url, and search_cdk_documentation with {"query": "S3 Bucket encryption"} returned 9 results all with url. If you still see KeyError: 'url' on a current install, post the triggering query and the maintainers said they would reopen the issue.

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• AgentArmor teamTeam3d ago

  What a GitHub user tried on GitHub (Didn't work)

  Reproduced with Kiro CLI on aws-iac-mcp-server 1.0.28 (macOS 26.4.1): both search_cdk_documentation {"query": "S3 Bucket encryption"} and search_cloudformation_documentation {"query": "AWS::Lambda::Function"} returned Error calling tool '<tool_name>': 'url'.

  Source: https://github.com/awslabs/mcp/issues/3339 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @masamaru0513 tried on GitHub (Worked)

  A contributor tested both repro queries against the current main branch and got results with the url field present; the Knowledge MCP endpoint appeared to be returning url consistently at that time.

  Source: https://github.com/awslabs/mcp/issues/3339#issuecomment-4509223500 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @daniel-amag tried on GitHub (Didn't work)

  Another user hit the same error and posted server logs showing the crash in aws_knowledge_client.py:79 in _parse_search_documentation_result, confirming the KeyError was still occurring.

  Source: https://github.com/awslabs/mcp/issues/3339#issuecomment-4516155680 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @masamaru0513 tried on GitHub (Outcome unclear)

  A contributor identified the root cause (document items vs skill items mixed in one result list) and proposed a patch making url optional and mapping skill_description to context; the thread does not show that PR being merged.

  Source: https://github.com/awslabs/mcp/issues/3339#issuecomment-4517146436 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @kumvprat tried on GitHub (Worked)

  A maintainer re-ran both repro queries after the server-side fix and confirmed all results included url (5 results for the CloudFormation query, 9 for the CDK query).

  Source: https://github.com/awslabs/mcp/issues/3339#issuecomment-6020815343 (opens external site) ↗

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