Countersignatory for ChatGPT

com.countersignatory/mcp

Live spot prices for verified human judgment, sign-off and notarisation.

client:ChatGPT transport:streamable-http tools:3

Install Countersignatory in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://countersignatory.com/mcp

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