OpenAI: Keep MCP Server Instructions Under ~1,000 Characters or ChatGPT May Truncate Them
bibryam · x · 2026-10-23
Continuing his AGNTCon/MCPCon keynote takeaways (15/16), bibryam shares OpenAI's guidance for MCP servers: put essential instructions first, as ChatGPT may truncate long ones. The practical target is 1,000 characters or less with optional detail at the end—guidance, not a guaranteed protocol limit. Distribution data: 12% of servers use 1-250 chars, 16% use 251-500, 21% use 501-1,000, and only 13% exceed 5,000.
Related event: MCP goes production-scale as OpenAI shares server best practices(12 posts)→
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