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How to add the ZeroWidth Caliper MCP server to ChatGPT

Server URL: https://api.zerowidth.ai/mcp/x/caliper
Sign-in: No sign-in. Paste the URL and it connects.
Our hands-on result: Partial 6 of 7 tasks passed, tested Oct 18, 2026 with MCP TypeScript SDK (reference client).

ChatGPT setup

https://api.zerowidth.ai/mcp/x/caliper
  1. Open Plugins on chatgpt.com, click the plus button, then Add custom MCP server. On some plans you first turn on Developer mode under Settings.
  2. Name it ai-zerowidth-caliper and enter the URL: https://api.zerowidth.ai/mcp/x/caliper
  3. Set authentication to none.
  4. Tick the risk acknowledgement, create it, then start a new chat and pick it with @.

We ran the hands-on test in a reference client, not in ChatGPT. This config follows ChatGPT's documented format for remote (Streamable HTTP) servers. If it fails for you, tell us and we will retest.

Same server, other clients

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