ChatGPT PostAgent create_letter
How to: ChatGPT PostAgent create_letter
Add PostAgent to ChatGPT
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01
Open Settings → Connectors → Advanced → Developer mode and merge this in. Keep any servers already there.
https://api.postagent.sh/mcp-
02
Save the file and restart ChatGPT.
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03
Ask for something create_letter does. ChatGPT lists the server's tools on connect and calls create_letter itself — you do not invoke it by name.
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04
If nothing happens, check the server is running and that PostAgent's identifier in your config matches the one above exactly.
Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs
Same tool, other clients
This list was read from the server itself, by connecting to it and calling tools/list on 24 September 2026. It is what
the server actually exposes, not what its listing claims.
Mutating and Read-only are read off each tool's name, not its schema — a hint, not a guarantee. The registry stores tool names only; connect the server for its live schemas.