marginal for ChatGPT

sh.marginal/mcp

Email A/B tests for AI agents: subject lines, managed sends, open/click tracking, and results.

client:ChatGPT transport:streamable-http

Install marginal in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://marginal.sh/mcp

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