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ChatGPT supports the Model Context Protocol (MCP) through the Apps SDK. Point ChatGPT at your Heroku manifest to expose tools, resources, and widgets inside conversations.

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Requirements

  • ChatGPT Developer Mode (request access in OpenAI settings).
  • An MCP server running on Heroku with a manifest served at /.well-known/mcp.json (see the remote server guide).

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Add a connector

  1. Deploy or update your Heroku MCP server. Copy the manifest URL, for example https://my-app.herokuapp.com/.well-known/mcp.json.
  2. In ChatGPT, open Settings → Builder tools → Connectors.
  3. Click Add MCP server, paste the manifest URL, and supply auth headers if required.
  4. Assign the connector to the GPTs or workspaces that should use the tools.
ChatGPT fetches the manifest, lists the available tools/resources/widgets, and invokes them automatically when the conversation matches their descriptions. Users can also call tools explicitly by name.

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Build a ChatGPT app

  • Use the ChatGPT app cookbook to bootstrap rich widgets and tool logic.
  • Keep tool descriptions specific so ChatGPT understands when to trigger them.
  • Monitor Heroku logs (heroku logs --tail) to verify tool invocations and diagnose errors.

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Tips

  • Long-running tasks should stream updates or return quickly with follow-up prompts.
  • Version your manifest—ChatGPT caches responses; changing the URL path (e.g., /mcp/v2.json) forces a refresh.
  • Coordinate with your team via Heroku Pipelines: review apps let you test manifest changes before promoting to production.