Skip to main content
The Fuse MCP server lets AI assistants operate your Fuse account directly: search for prospects, manage lists and campaigns, triage your inbox, pull analytics, and more — all through natural language. It implements the Model Context Protocol, so it works with Claude, Cursor, and any other MCP-capable client. It is a separate surface from the REST API. The REST API is for your own code and authenticates with API keys; the MCP server is for AI assistants and authenticates by signing in to your Fuse account — no API key involved.

​
Server URL

The same URL is shown in the Fuse app under Settings → MCP, with a copy button.

​
How authentication works

The server uses standard OAuth, which every major MCP client handles for you:
  1. The first time your assistant connects, it registers itself with Fuse automatically and opens a browser window.
  2. You sign in with your Fuse email and password and approve the connection.
  3. The assistant receives its own tokens and refreshes them silently from then on.
There is nothing to configure and no key to paste. The connection acts as you: tools run with your user’s permissions and see exactly the data your account sees. A connection that goes unused for about a month expires, and the client will ask you to sign in again.
A connected assistant can do what you can do in Fuse — including sending emails and modifying lists and campaigns — whenever you ask it to. Only connect clients you trust, and disconnect the server from the client’s settings when you no longer use it.

​
Set up your client

1

Claude (web and desktop)

Go to Settings → Connectors → Add custom connector, name it Fuse, paste https://mcp.tryfuse.ai as the URL, and click Add. Then click Connect and sign in with your Fuse credentials.
2

Claude Code

Then run /mcp inside a session and pick fuse to complete the sign-in.
3

Cursor

Add the server to ~/.cursor/mcp.json (or your project’s .cursor/mcp.json):
Cursor opens the sign-in flow the first time it connects.
4

Any other MCP client

Point the client at https://mcp.tryfuse.ai. Any client that supports the Streamable HTTP transport and OAuth works; everything it needs is discoverable from the URL.
Once connected, the client lists the Fuse tools automatically — see Tools & limits for what they can do.

​
For custom clients

Everything a hand-rolled client needs is served from the standard discovery endpoints:
  • GET https://mcp.tryfuse.ai/.well-known/oauth-protected-resource names the authorization server.
  • GET https://core.backend.tryfuse.ai/.well-known/oauth-authorization-server lists the registration, authorization, and token endpoints.
The OAuth flow is authorization code with PKCE (S256) for public clients (token_endpoint_auth_methods_supported: ["none"]), with dynamic client registration and the single scope mcp:tools. Access tokens last one hour; refresh tokens rotate on every refresh and last 30 days from their last use.The transport is stateless Streamable HTTP:
  • Send JSON-RPC messages with POST. Batches (arrays of messages) are accepted.
  • There is no server-push stream: GET is not supported, and no Mcp-Session-Id needs to be replayed between requests.
  • Supported protocol versions: 2025-11-25, 2025-06-18, 2025-03-26, and 2024-11-05 — the server negotiates down during initialize.
Unauthenticated requests receive 401 with a WWW-Authenticate header pointing at the resource metadata, which is the standard signal for clients to start the OAuth flow.

​
Troubleshooting

Still stuck? Write to support@fuseai.com with the client you’re using and roughly when the failure happened.