Remote MCP server

Connect Claude.ai, ChatGPT, or Cursor to the hosted 42A MCP server — no install required.

The same toolset that @42a/mcp ships locally is also hosted at:

https://mcp.42a.ai/mcp

It speaks the MCP Streamable-HTTP transport, so any remote-capable MCP client can use it. Nothing to install, nothing to keep updated.

Claude.ai (custom connector)

Go to Settings → Connectors → Add custom connector.
Name it 42A and set the URL to https://mcp.42a.ai/mcp.
Leave the advanced OAuth fields (client ID / secret) empty — the server supports automatic client registration.
Click Connect and sign in with your 42A account when prompted.

That's it — the 42A tools appear in Claude's tool picker, scoped to the account you signed in with.

ChatGPT

Add the connector under Settings → Apps & Connectors with the same URL, https://mcp.42a.ai/mcp. ChatGPT discovers the OAuth configuration automatically and walks you through the 42A sign-in.

Cursor and API-key clients

Clients that send static headers can skip OAuth entirely and authenticate with a 42A API key instead:

{
  "mcpServers": {
    "42a": {
      "url": "https://mcp.42a.ai/mcp",
      "headers": {
        "Authorization": "Bearer ck_live_...",
        "X-Org-Id": "org_2abcde"
      }
    }
  }
}

X-Org-Id is only needed for user keys that can access more than one org — org keys are already scoped.

Remote vs. local

	Remote (`mcp.42a.ai`)	Local (`@42a/mcp`)
Install	none	`npx -y @42a/mcp`
Auth	OAuth sign-in or API key	API key env var
Works in	Claude.ai, ChatGPT, Cursor, any Streamable-HTTP client	Claude Desktop, Claude Code, any stdio client
Updates	automatic	pinned to the npm version you run

Both wrap the same public API — pick whichever fits the client you're using.

Troubleshooting

Asked for a client ID / secret — leave those fields empty; they're optional. If the connector refuses to proceed without them, the discovery request may have been blocked by a corporate proxy — check that https://mcp.42a.ai/.well-known/oauth-protected-resource/mcp is reachable.
401 on every tool call — the OAuth token expired or the API key is revoked. Reconnect the connector, or mint a fresh key in Settings → API keys.
"X-Org-Id header is required" — you're using a user-scoped API key without an org header. Call list_organizations, then add the chosen org_xxx as X-Org-Id.

Last updated July 7, 2026