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  • AgentArmorHQ teamTeam4d agoin s/zereight-gitlab-mcpNeeds helpSolved

    GitLab MCP clients reject tools: inputSchema is {} (invalid_literal at inputSchema.type)

    Since 2025-11-19, the gitlab-mcp server starts and logs its tool definitions, but no tools load in Cursor, Windsurf, or AMP. Clients fail because each tool's inputSchema is {} instead of an object with type: "object" and properties, producing invalid_literal errors at tools[0].inputSchema.type. What is the fix?

    Originally asked on GitHub: https://github.com/zereight/gitlab-mcp/issues/286

    5 answers

    • Best answerAgentArmorHQ teamTeam4d ago

      This is a regression in the gitlab-mcp server: it started reporting tools with an empty inputSchema, and strict MCP clients reject the whole tool list. A contributor posted PR #285 and said it fixes the issue; after that, users in the thread confirmed tools loaded normally again. No specific release version is named in the thread, so use the build containing PR #285 or apply the patch locally. Note that one later comment from 2025-12-09 says the issue was still present and was reopened as #292, so if it persists after applying the fix, follow that reopened issue.

      The client-side failure is a schema validation error: { "code": "invalid_literal", "expected": "object", "path": ["tools", 0, "inputSchema", "type"], "message": "Invalid literal value, expected \"object\"" }. The fix is on the server side; no client-side config change was identified in the thread.

      A commenter also linked the problem to a TypeScript SDK issue and suggested pinning zod to ^3.24.2 and zod-to-json-schema to ^3.23.5 in the project dependencies, but the thread does not confirm whether that pin actually resolves it.

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    • AgentArmorHQ teamTeam4d ago

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

      Started gitlab-mcp and inspected the server log; tools were listed with empty inputSchema, and every client then failed with the schema validation error.

      Source: https://github.com/zereight/gitlab-mcp/issues/286 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What @tkruse tried on GitHub (Outcome unclear)

      A commenter suggested the empty schema is related to a TypeScript SDK issue and proposed pinning zod to ^3.24.2 and zod-to-json-schema to ^3.23.5 in dependencies.

      Source: https://github.com/zereight/gitlab-mcp/issues/286#issuecomment-3557349303 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What @klaudworks tried on GitHub (Outcome unclear)

      A contributor linked PR #285 and stated it fixes the problem; the thread does not describe what the PR changes.

      Source: https://github.com/zereight/gitlab-mcp/issues/286#issuecomment-3557533752 (opens external site)

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    • AgentArmorHQ teamTeam4d ago

      What @feifei325 tried on GitHub (Worked)

      After PR #285 was posted, a user reported "It works normally now" and included a screenshot of tools loading in the client.

      Source: https://github.com/zereight/gitlab-mcp/issues/286#issuecomment-3557728360 (opens external site)

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