gmail-mcp

A remote Gmail MCP server you host yourself and add to Claude as a custom connector. Once it's connected, the connector works everywhere you use Claude: claude.ai, desktop, mobile, and Claude Code.

• Google sign-in when you connect. Pick a Gmail account when you add the connector. One deployment can serve several accounts; add one connector per inbox. claude.ai won't add the same URL twice, so give each extra inbox its own path: /mcp/work, /mcp/personal (lowercase letters, digits and -).

• No database. Every token is encrypted with your SECRET and contains everything the server needs to read it back.

• Allowlist. Only the Google accounts in ALLOWED_EMAILS can connect.

Tools

Scope is gmail.modify: read, send, label, trash. It can't permanently delete anything.

Related MCP server: Gmail MCP Server

Deploy

1. Railway

New project → Deploy from GitHub repo → your fork. Then Settings → Networking → Generate Domain. Note the domain, e.g. gmail-mcp-production.up.railway.app.

Any Node host works. Set BASE_URL if you're not on Railway.

2. Google OAuth client

In Google Cloud Console:

1. Create a project and enable the Gmail API.

2. Google Auth Platform → Branding: fill in an app name and your email.

3. Audience: External. Then Publish app. If you leave it in Testing, Google expires refresh tokens after 7 days and you'll have to reconnect weekly. An unverified app in production works fine for personal use; you'll click through an "unverified app" warning once.

4. Clients → Create client → Web application. Add this authorized redirect URI:

   https://<your-domain>/oauth/google/callback

3. Environment

4. Connect

Go to claude.ai → Settings → Connectors → Add custom connector, use https://<your-domain>/mcp, then sign in with Google.

How auth works

Claude ──/authorize──▶ server ──▶ Google sign-in ──▶ /oauth/google/callback
       ◀──code──────── server ◀───────────────────────┘
Claude ──/token──────▶ server   (access token wraps the Google refresh token)
Claude ──/mcp────────▶ server ──▶ Gmail API

The server acts as an OAuth 2.1 authorization server, with dynamic client registration and PKCE, through the MCP SDK's mcpAuthRouter. Google handles the actual sign-in. Client IDs, auth codes, and tokens are AES-256-GCM-encrypted payloads, so nothing is stored on the server.

Trade-offs of storing nothing:

• No server-side revocation. To cut off access, remove the email from ALLOWED_EMAILS (checked on every hourly token refresh), rotate SECRET, or revoke the app at myaccount.google.com/permissions.

• Auth codes aren't single-use within their 10-minute window. PKCE still ties each code to the client that requested it.

Develop

cp .env.example .env   # add http://localhost:3000/oauth/google/callback to your Google client
pnpm install
pnpm dev
pnpm check             # tsc + biome

License

MIT