MCP

Connect Cursor, VS Code and Codex

Add the MISSIN MCP server to Cursor, VS Code, Codex or any client that speaks Streamable HTTP or stdio, with a secret key kept out of your repository.

The hosted MCP server at https://api.missin.co.uk/mcp works with any client that can send a header on Streamable HTTP, and npx -y @missin/cli mcp serves the same tools over stdio for any client that starts a command. Both take a secret key, and both give the assistant the key's access level and no more. Connect Claude has the Claude routes and the access levels.

Create the key in . It is shown once. Pick Read to let the assistant look only, or Write to let it change partners, campaigns and posts and start captures.

Add the server

Cursor reads ~/.cursor/mcp.json for every project, or .cursor/mcp.json in one project. Put the key in your shell environment, start Cursor from that shell, and refer to it:

json

{
  "mcpServers": {
    "missin": {
      "url": "https://api.missin.co.uk/mcp",
      "headers": {
        "Authorization": "Bearer ${env:MISSIN_API_KEY}"
      }
    }
  }
}

Cursor resolves ${env:NAME} in url and headers. To load more tools, add toolsets to the URL, for example https://api.missin.co.uk/mcp?toolsets=forms,waitlists.

To run the server on your own machine instead, give Cursor a command:

json

{
  "mcpServers": {
    "missin": {
      "command": "npx",
      "args": ["-y", "@missin/cli", "mcp"],
      "env": { "MISSIN_API_KEY": "${env:MISSIN_API_KEY}" }
    }
  }
}

Let an agent install it

The copyable install prompt on Connect Claude covers Claude Code, Codex and Cursor: the agent checks the endpoint, asks for the key without echoing it, adds the server and calls whoami.

Check it works

Ask the assistant "which workspace are you connected to, and what can you change?". It calls whoami, which answers with the workspace, the key's name and its access level. If the server shows as failed, see the troubleshooting list in Connect Claude: a 401 is a missing or revoked key, and a 403 with secret_key_required is a publishable key.

Sources

The vendors' own docs for Cursor's MCP configuration, VS Code's MCP configuration reference and Codex's MCP configuration. ChatGPT's own custom MCP servers offer OAuth or no authentication only (Add custom MCP server), so they cannot send a MISSIN key.