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Fix: tools/call with an unknown tool name returns -32602

Web-audit fix skill for the mcp-unknown-tool check (MCP, SHOULD).

Goal

Reject an unknown tool name with -32602 instead of a hang, a 500, or a fake result.

Fix

Answer a tools/call whose params.name matches no registered tool with error.code: -32602 (Invalid params). Agents rely on the code to distinguish "no such tool" from a transport failure; a hang, a 500, or a 200 result for a tool that does not exist all read as a broken server.

Resources

Copy-paste prompt

Paste this into your coding agent. Your audit adds what it observed for this check:

Verify

Re-run the audit at https://anc.dev/audit or call the audit_website MCP tool; the mcp-unknown-tool check should report pass.