Connect Cursor to thirds.ai

Use thirds.ai tools in Cursor Agent to build templates and create PDFs or images. Create an API key on the API keys page first.

Install the server

Set THIRDS_API_KEY in the environment that starts Cursor. Then create ~/.cursor/mcp.json for all projects, or .cursor/mcp.json for one project:

{
  "mcpServers": {
    "thirds": {
      "url": "https://thirds.ai/mcp",
      "headers": {
        "Authorization": "Bearer ${env:THIRDS_API_KEY}"
      }
    }
  }
}

Cursor supports Streamable HTTP servers, request headers, and environment variable interpolation in mcp.json. See the Cursor MCP guide. Keep the key out of the file and source control.

Check the connection

Open Cursor settings, select Tools & MCP, and enable thirds. In Cursor Agent you can also run agent mcp list and agent mcp list-tools thirds.

Ask the agent to list the thirds.ai tools. Then read the main MCP guide for safe credit approval, retries, and status checks.

FAQ

Why does Cursor not see the environment variable?

Start Cursor from an environment that has THIRDS_API_KEY, or add the variable to the system environment used by the app. Restart Cursor after you change it.

Which configuration file should I use?

Use ~/.cursor/mcp.json for your own global setup. Use .cursor/mcp.json to share the server definition with a project. Each user still needs a private key.

Does connecting spend credits?

No. Connecting and listing tools don't spend credits. AI template work and successful renders can. Ask your agent to show the action and the cost before it starts paid work.