FetchSandbox for ChatGPT

io.github.fetchsandbox/mcp

A deterministic verification engine for agents. Proves a fix: fails on the old code, passes on new.

client:ChatGPT transport:streamable-http runtime:npm tools:17

Install FetchSandbox in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://fetchsandbox.com/mcp/v1

Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs