Connect Cantrip to your AI assistant (MCP)

Cantrip is the simple website builder at cantrip.io. It runs a hosted MCP server so you can build and manage your website by talking to an AI assistant — Claude, ChatGPT, Cursor, or any MCP-compatible client.

Heads up: This is Cantrip.io, the website builder — not "Cantrip.ai" or any other product. Always use the hosted endpoint above. There is no npx/stdio package to install.

The one thing you need

MCP endpoint URL (paste this into your AI client):

https://www.cantrip.io/mcp

Authentication: OAuth. Authorize in your AI client and sign in to Cantrip when prompted. No API key to copy or paste.

Connect it

ChatGPT

Settings → Connectors (enable Developer Mode if your plan requires it) → Create / Add custom connector → paste the endpoint URL → choose OAuth → Authorize and sign in to Cantrip.

Claude (web or desktop)

Settings → Connectors → Add custom connector → paste the endpoint URL → Add → Authorize.

Cursor

Add the snippet below to ~/.cursor/mcp.json (or the project .cursor/mcp.json), reload, then approve the OAuth prompt on first use.

{"mcpServers":{"cantrip":{"url":"https://www.cantrip.io/mcp"}}}

Claude Code (CLI)

Run the command below, then use /mcp inside Claude Code to complete the OAuth login.

claude mcp add --transport http cantrip https://www.cantrip.io/mcp

First things to try

Once connected, ask your assistant:

  • “List my Cantrip websites.”
  • “Add a Services page to my site with a section for each service.”
  • “Generate an About page from this description: ...”
  • “Switch my site to the Paladin theme and publish.”

Advanced: headless / automation

OAuth is the only way in to the hosted MCP endpoint — it is behind the OAuth guard, so a Cantrip API token in an Authorization header is rejected before any tool runs. For headless automation, use the V1 REST API at /api/v1 instead: get a token with POST /api/v1/auth/token and send it as Authorization: Bearer <token>. The REST API covers the same capabilities as the MCP tools.

Machine-readable version of this page: /api/v1/mcp/connection

Troubleshooting

  • Your assistant mentions “Cantrip.ai” or npx mcp-server-cantrip — it's guessing. Cantrip.io is hosted; always use the endpoint above.
  • “Connection failed / 401” — you aren't authorized yet. Re-run the connector's Authorize step and sign in to your Cantrip account.
  • No websites listed — you may be signed in to the wrong account, or have no site yet. Create one at cantrip.io first.
  • ChatGPT won't let you add a connector — your plan or workspace may not have Developer Mode / custom connectors enabled. Use Claude or Cursor in the meantime.