gmail-mcp

A local MCP server that gives Claude access to several Gmail accounts at once — search, read, draft, send, label, and a scheduled cross-inbox digest — without switching mailboxes.

Runs entirely on your machine. Nothing is hosted; mail goes only to Google.

The problem

Running several mailboxes — personal, sales, support, billing — means switching between them all day. AI assistants don't fix it: they connect to one account, or take broad access with no way to say this one may send, that one may not. Unrestricted send access to a client-facing address is why most people never connect one at all.

Related MCP server: Gmail MCP Server

Who it's for

Freelancers, agencies and small teams with several Gmail or Workspace mailboxes who want an assistant across all of them, and a hard guarantee about what it can send.

What it does

Ten tools, each taking an explicit account alias so the mailbox is never ambiguous.

Send safety is the core design decision. Each mailbox declares send, confirm, or draft_only in config, enforced in code rather than in a prompt — so neither the model nor anything written into the mail it reads can talk it out of it. check_inboxes reads untrusted email on a schedule, which is exactly why that control can't live in an instruction.

Architecture

flowchart TD
    H["Claude Desktop · Claude Code"] -->|stdio| S["server.py<br/>10 tools — validate, delegate, shape"]
    S --> P{"send policy gate<br/>send · confirm · draft_only"}
    P -->|blocked| D["draft"]
    P -->|allowed| T["transmit"]
    S --> G["gmail/<br/>search · messages · compose · labels"]
    S --> C["check.py<br/>parallel watermarked sweep"]
    G --> CL["client.py<br/>retry · error mapping · per-account cache"]
    C --> CL
    T --> CL
    CL --> A["auth.py — OAuth refresh"]
    A --> ST["storage.py<br/>OS keyring, or 0600 file"]
    CL --> API[("Gmail API — gmail.modify")]

Every Gmail call passes through one choke point owning retries and error mapping, and each account gets its own service object — which is what makes the parallel sweep safe. check_inboxes keeps a per-account watermark, so a scheduled run reports only genuinely new mail.

Setup

Full guide: docs/SETUP.md.

1. Google Cloud — enable the Gmail API, configure an OAuth consent screen (Internal for a Workspace domain, External for consumer Gmail), add the single scope gmail.modify, create a Desktop app OAuth client, and save the JSON as client_secret.json in your config directory.

2. Install

git clone <this repo> && cd gmail-mcp
uv sync
cp config.example.toml <config-dir>/config.toml   # then edit it
uv run gmail-mcp auth add <alias>                 # once per account
uv run gmail-mcp doctor                           # verify every account

3a. Claude Code — any OS:

claude mcp add gmail --scope user -- \
  /absolute/path/to/uv --directory /absolute/path/to/gmail-mcp run gmail-mcp serve

3b. Claude Desktop — add to claude_desktop_config.json:

{
  "mcpServers": {
    "gmail": {
      "command": "/absolute/path/to/uv",
      "args": ["--directory", "/absolute/path/to/gmail-mcp",
               "run", "gmail-mcp", "serve"]
    }
  }
}

Absolute paths in both: neither host inherits a shell PATH, and a bare command name is the usual reason a server silently fails to start.

Demo

📹 Recording: add link here

Local server, so no hosted instance. Two moves:

1. "Check all my inboxes and tell me what needs my attention." Ask again — nothing new, because each account remembers where it got to.

2. "Send this from my personal account." It returns a draft and names the policy that stopped it.

Design notes

• Least privilege. One scope, gmail.modify — which cannot permanently delete mail. Chosen, not inherited.

• Credentials live in the OS keyring (Keychain, Credential Manager, Secret Service), falling back to a 0600 file. Deliberately not encrypted: the server starts unattended, so any key would sit beside the ciphertext.

• Failure isolation. A revoked token fails one mailbox and names the fix; the others keep working.

• Correct replies. In-Reply-To and References are set, so replies thread in Outlook and Apple Mail — not only Gmail.

• Cross-platform via platformdirs and keyring.

Development

uv sync && uv run pytest

193 tests, written test-first, running offline against a fake Gmail API — no network, credentials, or live mailbox needed. One opt-in integration test covers the real OAuth round trip.

License

MIT