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fix(mcp): return structured error with valid tool list on unknown tool - #561
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October 19, 2026 17:56
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Summary
Closes #415
Returns a structured error with a code and the list of valid tool names when an unknown tool is called, instead of throwing a raw protocol-level exception.
Changes
throw new Error(\Unknown tool: ...`)with structured error response usingERR_UNKNOWN_TOOL`.validTools: ['bazaar_search', 'paid_call']in the error response and message so calling agents can inspect and self-correct immediately.Tests
tests/mcp.test.ts:returns a structured error instead of throwing a raw exceptionlists all valid tool names in the error responselength-bounds and sanitises untrusted input in tool name echonpx vitest run tests/mcp.test.ts).