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Where Claude Code puts your MCP server's instructions: in a user turn, not the system prompt, cut at 2,048 characters

This story is from 2026-10-07. It is preserved in the archive; the latest stories are on the live feed.

20 of 20 claude -p runs on Claude Code 2.1.285 opened our stdio MCP server with server/discover , a probe the docs say stdio servers only get when MCP_PROTOCOL_NEGOTIATION=auto is set, and in the 2 runs where the server answered it, initialize was never sent, so the instructions we had put in the i…

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  1. 2026-10-07 02:17 · DEV Community — AI
    Where Claude Code puts your MCP server's instructions: in a user turn, not the system prompt, cut at 2,048 characters

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