Gmail MCP Server

Public Gmail MCP server — Streamable HTTP + OAuth 2.1, same architecture as the Salesforce and Outlook MCP Servers. One deployed URL works with:

• Archon AI portal (Managed MCP via Anthropic / OpenAI)

• Claude.ai custom connectors

• ChatGPT custom MCP

• Any standalone MCP client (n8n, Cursor, custom apps) via the PATH B flow

Tools (11)

Related MCP server: Gmail MCP Server

Setup

1. Google Cloud OAuth client (one-time)

1. https://console.cloud.google.com → create/select a project

2. APIs & Services → Library → enable Gmail API

3. OAuth consent screen → External → add scope https://www.googleapis.com/auth/gmail.modify (+ openid, email, profile). While the app is in Testing status, add your Gmail address under Test users — otherwise login fails with access_denied.

4. Credentials → Create credentials → OAuth client ID → Web application Authorized redirect URIs:

   • https://claude.ai/api/mcp/auth_callback (Claude connector)

   • <BASE_URL>/auth/callback (PATH B standalone)

2. Run

cp .env.example .env      # fill in GOOGLE_CLIENT_ID / GOOGLE_CLIENT_SECRET / BASE_URL
npm install
npm run dev               # http://localhost:3200

3. Deploy (Render)

• Build command: npm install

• Start command: npm start

• Env vars: BASE_URL (the Render URL), GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET, GOOGLE_REDIRECT_URI=<BASE_URL>/auth/callback

• After deploy, add <BASE_URL>/auth/callback to the Google OAuth client's redirect URIs.

Auth paths

PATH A — Bearer header (portals, Claude connector). The client sends Authorization: Bearer <google access token> on /mcp. Tokens acquired through this server's /token proxy get vaulted, enabling server-side refresh when Google returns 401 (Google access tokens live ~1 hour).

PATH B — session flow (standalone clients). Visit <BASE_URL>/auth?session=<id> → Google login → tokens stored server-side keyed by the stable Google account id.

The /authorize proxy forces access_type=offline&prompt=consent so Google actually issues a refresh token, and both proxies force the real Google client credentials so Dynamic Client Registration (Claude invents a random client id) still works — the only requirement is the client's redirect URI being whitelisted on the Google OAuth client.

Gmail-specific notes

• Gmail message ids are opaque hex strings; always source them from listEmails/searchEmails in the same session.

• Gmail has labels, not folders. moveEmail maps the familiar folder actions: archive = remove INBOX, trash = the dedicated trash endpoint.

• replyEmail fetches the original's Message-ID/References headers and sends with threadId, so replies thread correctly in both Gmail and the recipient's client.