Connect Cantrip to an AI assistant

Cantrip is the simple website builder at cantrip.io. There are two ways to manage your site by talking to an AI, depending on what your assistant supports:

  • Full access via MCP — Claude (any plan, including Free), Cursor, Claude Code, and ChatGPT in Developer Mode (Pro/Business/Enterprise) connect directly, no curation, everything the portal can do.
  • A safe-write API for everything else — ChatGPT on Free or Plus, Gemini, and other tools that can't add a live MCP connector use a published OpenAPI schema instead.
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.

MCP — full access

For Claude (any plan — Free included), Cursor, Claude Code, and ChatGPT Developer Mode (Pro, Business, or Enterprise).

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

Custom connectors need Developer Mode, which requires ChatGPT Pro, Business, or Enterprise — Free and Plus can't add one. Settings → Connectors → enable Developer Mode → Create / Add custom connector → paste the endpoint URL → choose OAuth → Authorize and sign in to Cantrip.

Claude (web or desktop)

Works on every plan, including Free (capped at one custom connector there — Cantrip counts as it). 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

Everyone else — a safe-write API

For ChatGPT Free/Plus, Gemini, and any other tool that reads an OpenAPI schema instead of speaking MCP directly.

A curated, safe-write subset of the Cantrip API (list/get websites, pages, and sections; edit page and section content; switch themes; update appearance; generate AI content) described as an OpenAPI 3.1 schema, OAuth-protected by the same authorization server as the MCP endpoint. For AI platforms and clients that cannot add a live MCP connector.

  • List your websites and pages
  • Read and edit page section content
  • Switch themes and update colors/appearance
  • Generate AI website copy

Publishing, deleting, billing, domains, and team management stay MCP/portal-only for now.

OpenAPI schema: https://www.cantrip.io/openapi/cantrip-api.yaml
OAuth authorization URL: https://www.cantrip.io/oauth/authorize
OAuth token URL: https://www.cantrip.io/oauth/token

ChatGPT (Free or Plus)

Free and Plus plans can't add a custom connector, but they can use a Custom GPT someone else built and published — including one built on this schema. If you (or a developer you work with) have a paid ChatGPT account:

  1. In ChatGPT, go to Explore GPTs → Create, then open the Configure tab.
  2. Under Actions, click Create new action and import the schema URL above.
  3. Set Authentication to OAuth: paste the authorization and token URLs above, plus a Client ID and Secret (Cantrip staff: generate one with php artisan passport:client).
  4. Save once, copy the callback URL ChatGPT now shows you, and update the OAuth client's redirect URI to that exact value.
  5. Publish the GPT (link-only or the public GPT Store). Anyone who opens it — any ChatGPT plan — will be prompted to sign in to Cantrip on first use.

Gemini, or your own integration

Point any OpenAPI-aware tool (Gemini function calling/Extensions, LangChain, a custom agent) at the schema URL above. It's a standard OpenAPI 3.1 document with an OAuth2 authorization-code security scheme — no Cantrip-specific client library needed.

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 — Free and Plus plans can't add custom MCP connectors at all; that's an OpenAI plan restriction, not a Cantrip limitation. Use the safe-write API / Custom GPT path instead, or a plan with Developer Mode.