io.github.gx-55/multi-gmail-mcp MCP Server

multi-gmail-mcp

A Model Context Protocol (MCP) server that lets Claude Desktop manage multiple Gmail accounts simultaneously. Listed on the official Anthropic MCP registry and published on npm.

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Features

• Connect unlimited Gmail accounts — personal, work, side projects
• Search any inbox using full Gmail search syntax
• Read complete emails with MIME parsing
• Send, reply in thread, and create drafts
• Organize with labels: add, remove, list, archive
• Mark as read / unread
• Tokens stored locally in ~/.gmail-mcp-tokens.db — never committed to git
• Auto-refreshes OAuth tokens silently

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Requirements

• Node.js >= 22.5.0
• A Google Cloud project with the Gmail API enabled
• Claude Desktop

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Installation

npm install -g multi-gmail-mcp

This registers two global commands: gmail-mcp (the MCP server) and gmail-mcp-cli (account manager).

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Google Cloud Setup

You only need to do this once.

1. Go to console.cloud.google.com → create a project
2. Enable the Gmail API (APIs & Services → Library)
3. Configure the OAuth consent screen — External, add your Gmail addresses as test users
4. Add scopes: gmail.readonly, gmail.send, gmail.modify, gmail.labels
5. Create a Desktop app OAuth credential → download the JSON
6. Save it to ~/.gmail-mcp-oauth.json

Alternatively, set environment variables in the Claude Desktop config (see below).

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Authenticating Gmail Accounts

# Add accounts (opens browser for Google sign-in)
gmail-mcp-cli add personal@gmail.com
gmail-mcp-cli add work@company.com

# List authenticated accounts
gmail-mcp-cli list

# Remove an account
gmail-mcp-cli remove work@company.com

Tokens are saved to ~/.gmail-mcp-tokens.db and refreshed automatically.

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Claude Desktop Configuration

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "multi-gmail": {
      "command": "gmail-mcp"
    }
  }
}

If you prefer environment variables over ~/.gmail-mcp-oauth.json:

{
  "mcpServers": {
    "multi-gmail": {
      "command": "gmail-mcp",
      "env": {
        "GOOGLE_CLIENT_ID": "your-client-id.apps.googleusercontent.com",
        "GOOGLE_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

Restart Claude Desktop after saving. Click the hammer icon to confirm 19 tools are loaded.

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Available Tools

Account Management

Tool	Description
list_accounts	List all authenticated Gmail accounts
initiate_auth	Start OAuth flow — returns a URL to open in browser
complete_auth	Finalize auth after completing Google sign-in
remove_account	Remove an account and its stored credentials

Reading Email

Tool	Description
search_emails	Search with Gmail syntax (is:unread, from:, after:, etc.)
get_email	Fetch full email content by message ID

Writing Email

Tool	Description
send_email	Send an email (supports To, CC, BCC)
reply_to_email	Reply in thread, preserving References headers
create_draft	Save an email as a draft

Organization

Tool	Description
list_labels	List all Gmail labels for an account
add_label	Add one or more labels to a message
remove_label	Remove one or more labels from a message
archive_email	Remove from Inbox
mark_as_read	Remove the UNREAD label
mark_as_unread	Add the UNREAD label

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Example Prompts

List all my authenticated Gmail accounts.

Search my work@company.com inbox for unread emails from this week.

Reply to that email from my personal account saying I'll be there Saturday.

Send an email from personal@gmail.com to friend@example.com
with subject "Dinner plans" and body "Are you free Saturday?"

Archive everything older than a week in my side-project inbox that's already read.

Check both my accounts for emails from GitHub and summarize them.

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Security

• ~/.gmail-mcp-oauth.json and ~/.gmail-mcp-tokens.db live in your home directory — outside the project, never committed
• .gitignore excludes *.db, .gmail-mcp-oauth.json, and .env
• The server runs over stdio only — no network port is opened
• OAuth scopes are limited to the minimum required

See SECURITY.md for full details: token storage, network behavior, scope rationale, revocation steps, and how to report a vulnerability.

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Registry

Listed on the official Anthropic MCP registry:

io.github.gx-55/multi-gmail-mcp

curl "https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.gx-55"

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Project Structure

multi-gmail-mcp/
├── bin/
│   ├── gmail-mcp.js        # Entry point for the MCP server command
│   └── gmail-mcp-cli.js    # Entry point for the CLI command
├── src/
│   ├── server.js           # MCP server — all 19 tools
│   ├── gmail-client.js     # Gmail API wrapper
│   ├── auth.js             # OAuth2 flow with auto-refresh
│   ├── db.js               # SQLite token storage (node:sqlite)
│   └── cli.js              # Account management CLI
└── package.json

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Troubleshooting

"No OAuth credentials found" Make sure ~/.gmail-mcp-oauth.json exists or set GOOGLE_CLIENT_ID / GOOGLE_CLIENT_SECRET in the Claude Desktop config.

"Account not found. Authenticate it first" Run gmail-mcp-cli add your@gmail.com before using that account in Claude.

Tools not appearing in Claude Desktop Confirm gmail-mcp is in your PATH (which gmail-mcp) and restart Claude Desktop.

Token expired errors Tokens auto-refresh if a valid refresh token is stored. If refresh fails, remove the account and re-authenticate: gmail-mcp-cli remove your@gmail.com && gmail-mcp-cli add your@gmail.com.