ai-tool

Model Context Protocol

14 verified traps, most recently checked first.

• 400 HeaderMismatch from an MCP server on protocol 2026-07-28

  400 Bad Request with a HeaderMismatch JSON-RPC error, code -32020

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• mcp-publisher fails with 'NPM package is missing required mcpName field' although package.json has it

  NPM package '@scope/name' is missing required 'mcpName' field

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP Registry cannot verify a Cargo crate that hides mcp-name in an HTML comment

  Publishing a crates.io server fails ownership verification

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP server log messages stop reaching the client after moving to protocol 2026-07-28

  notifications/message from the server no longer appear in the client

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP server on SDK v2 starts fine but tools/list fails because package.json still allows Zod 3

  client.listTools() returns an error pointing at fromJsonSchema() while the server keeps running

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP server returns 400 or 404 on session id after initialize when it runs on several instances

  400 Bad Request on calls after a successful initialize

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP tool names with dots are valid in MCP but rejected when forwarded to the Claude API

  400 invalid_request_error on a tools[].name when a custom client passes MCP tools straight to Claude

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP TypeScript client fails with SdkError ERA_NEGOTIATION_FAILED against an older server

  ERA_NEGOTIATION_FAILED: Version negotiation failed: the server did not offer pinned protocol version 2026-07-28 via server/discover (no fallback in pin mode)

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• MCP TypeScript client gives 'MCP error -32001: Request timed out' after 60 seconds on a long tool

  McpError: MCP error -32001: Request timed out

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• Python MCP server behind a proxy or custom domain rejects every request with 421 Invalid Host header

  421 Misdirected Request with body Invalid Host header in the server log

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• server.tool is not a function, or SSEServerTransport is missing, after upgrading the MCP TypeScript SDK to v2

  TypeError: server.tool is not a function

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• stdio MCP server fails with 'Unexpected token ... is not valid JSON' because something printed to stdout

  SyntaxError: Unexpected token ... is not valid JSON in the host's MCP log

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• Streamable HTTP MCP server answers 406 Not Acceptable to a hand-written client

  Not Acceptable: Client must accept both application/json and text/event-stream

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

• TS2589 'Type instantiation is excessively deep and possibly infinite' when registering MCP tools

  TS2589: Type instantiation is excessively deep and possibly infinite

  Model Context Protocol · verified 2026-10-15 · 0 confirmations

claude mcp add --transport http footgun https://getfootgun.com/api/mcp