MCP Gmail Server

A Model Context Protocol (MCP) server that provides read-only access to Gmail messages. This server enables searching, reading, and organizing Gmail messages with support for labels, threads, attachments, and batch operations.

Features

Mailbox Operations

• List messages with pagination and filtering
• Get full message content including headers and body
• Search messages using Gmail's powerful query syntax
• List all labels/folders in the account

Message Details

• List message attachments with metadata
• Get full email threads (conversations)
• List conversation threads with pagination

Filters & Organization

• Search by label - Filter messages by specific labels
• Search by date range - Find messages within date ranges
• Get unread counts - Statistics for unread messages

Batch Operations

• Batch get messages - Retrieve up to 100 messages in parallel for better performance

Installation

Install the server using Claude Code:

# Install with user scope for global availability
claude mcp add gmail -s user \
  -e GMAIL_CLIENT_ID=your-client-id \
  -e GMAIL_CLIENT_SECRET=your-client-secret \
  -e GMAIL_REFRESH_TOKEN=your-refresh-token \
  -- npx @chinchillaenterprises/mcp-gmail

# Or install with project scope for team sharing
claude mcp add gmail -s project \
  -e GMAIL_CLIENT_ID=your-client-id \
  -e GMAIL_CLIENT_SECRET=your-client-secret \
  -e GMAIL_REFRESH_TOKEN=your-refresh-token \
  -- npx @chinchillaenterprises/mcp-gmail

Authentication Setup

This server uses OAuth2 for authentication. You'll need three credentials:

• Client ID: Your OAuth2 client ID
• Client Secret: Your OAuth2 client secret
• Refresh Token: A long-lived token for accessing Gmail

Step-by-Step OAuth Setup

1. Create a Google Cloud Project

1. Go to Google Cloud Console
2. Create a new project or select an existing one
3. Enable the Gmail API:
   • Go to "APIs & Services" → "Library"
   • Search for "Gmail API"
   • Click on it and press "Enable"

2. Create OAuth2 Credentials

1. Go to "APIs & Services" → "Credentials"
2. Click "Create Credentials" → "OAuth client ID"
3. Configure consent screen if prompted:
   • Choose "External" (or "Internal" for Google Workspace)
   • Fill in required fields
   • Add your email to test users
4. For Application type, choose "Desktop app"
5. Name it (e.g., "MCP Gmail")
6. Click "Create"
7. Save your Client ID and Client Secret

3. Get a Refresh Token

Option A: Use the provided helper script

1. Save this script as get-gmail-token.js:

const { google } = require('googleapis');
const http = require('http');
const url = require('url');
const open = require('open');

const CLIENT_ID = 'YOUR_CLIENT_ID';
const CLIENT_SECRET = 'YOUR_CLIENT_SECRET';
const REDIRECT_URI = 'http://localhost:3000/oauth2callback';
const SCOPES = ['https://www.googleapis.com/auth/gmail.readonly'];

async function getRefreshToken() {
  const oauth2Client = new google.auth.OAuth2(CLIENT_ID, CLIENT_SECRET, REDIRECT_URI);
  
  const authUrl = oauth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
    prompt: 'consent'
  });

  console.log('Opening browser for authorization...');
  open(authUrl);

  const server = http.createServer(async (req, res) => {
    const queryObject = url.parse(req.url, true).query;
    if (queryObject.code) {
      const { tokens } = await oauth2Client.getToken(queryObject.code);
      console.log('\nREFRESH TOKEN:', tokens.refresh_token);
      res.end('Success! Check your terminal for the refresh token.');
      process.exit(0);
    }
  });

  server.listen(3000);
}

getRefreshToken();

2. Install dependencies and run:

npm install googleapis open
node get-gmail-token.js

Option B: Use OAuth Playground

1. Go to OAuth 2.0 Playground
2. Click settings (gear icon) → Use your own OAuth credentials
3. Enter your Client ID and Secret
4. Select "Gmail API v1" → https://www.googleapis.com/auth/gmail.readonly
5. Authorize and exchange for tokens
6. Copy the Refresh Token

Environment Variables

Set your credentials:

export GMAIL_CLIENT_ID="your-client-id"
export GMAIL_CLIENT_SECRET="your-client-secret"
export GMAIL_REFRESH_TOKEN="your-refresh-token"

Available Tools

Mailbox Operations

gmail_list_messages

List messages with various filters and pagination.

Parameters:

• maxResults (optional): Maximum messages to return (1-500, default: 100)
• pageToken (optional): Token for pagination
• labelIds (optional): Array of label IDs to filter by
• q (optional): Gmail search query
• includeSpamTrash (optional): Include SPAM and TRASH messages (default: false)

Example:

{
  "maxResults": 50,
  "labelIds": ["INBOX"],
  "q": "is:unread"
}

gmail_get_message

Get complete message content including headers and body.

Parameters:

• messageId (required): The message ID
• format (optional): Format - "minimal", "full", "raw", "metadata" (default: "full")

Returns: Message with headers, body (text and HTML), labels, and metadata.

gmail_search_messages

Search messages using Gmail's query syntax.

Parameters:

• query (required): Gmail search query
• maxResults (optional): Maximum results (1-500, default: 100)
• pageToken (optional): Pagination token
• includeSpamTrash (optional): Include SPAM/TRASH (default: false)

Example queries:

• from:user@example.com
• is:unread subject:"Important"
• has:attachment larger:5M
• after:2024/1/1 before:2024/12/31

gmail_list_labels

List all labels/folders in the Gmail account.

No parameters required.

Returns: Array of labels with IDs, names, and types (system/user).

Message Details

gmail_get_attachments

List all attachments in a message.

Parameters:

• messageId (required): The message ID

Returns: Array of attachments with filename, MIME type, size, and attachment ID.

gmail_get_thread

Get a complete email thread (conversation).

Parameters:

• threadId (required): The thread ID
• format (optional): Format for messages - "minimal", "full", "metadata" (default: "full")

Returns: Thread with all messages in the conversation.

gmail_list_threads

List conversation threads.

Parameters:

• maxResults (optional): Maximum threads (1-500, default: 100)
• pageToken (optional): Pagination token
• labelIds (optional): Filter by label IDs
• q (optional): Gmail search query
• includeSpamTrash (optional): Include SPAM/TRASH (default: false)

Filters & Organization

gmail_search_by_label

Get messages filtered by a specific label.

Parameters:

• labelId (required): Label ID to filter by
• maxResults (optional): Maximum results (1-500, default: 100)
• pageToken (optional): Pagination token

gmail_search_by_date

Search messages within date ranges.

Parameters:

• after (required): Start date (YYYY/MM/DD)
• before (optional): End date (YYYY/MM/DD)
• maxResults (optional): Maximum results (1-500, default: 100)
• pageToken (optional): Pagination token
• additionalQuery (optional): Additional search criteria

Example:

{
  "after": "2024/06/01",
  "before": "2024/06/30",
  "additionalQuery": "from:important@example.com"
}

gmail_get_unread_count

Get unread message statistics.

Parameters:

• labelIds (optional): Count unread in specific labels (default: ["INBOX"])

Returns: Total unread count and breakdown by label.

Batch Operations

gmail_batch_get_messages

Retrieve multiple messages efficiently in parallel.

Parameters:

• messageIds (required): Array of message IDs (max 100)
• format (optional): Format for all messages - "minimal", "full", "metadata" (default: "full")

Benefits:

• Much faster than individual requests
• Reduces API quota usage
• Returns all messages in one response

Usage Examples

Basic Email Search

// Search for unread emails from a specific sender
{
  "tool": "gmail_search_messages",
  "args": {
    "query": "from:boss@company.com is:unread",
    "maxResults": 20
  }
}

// Get the full content of a message
{
  "tool": "gmail_get_message",
  "args": {
    "messageId": "18f5c3a2b8e9d6f1"
  }
}

Working with Labels

// List all labels
{
  "tool": "gmail_list_labels"
}

// Get messages in a specific label
{
  "tool": "gmail_search_by_label",
  "args": {
    "labelId": "Label_123",
    "maxResults": 50
  }
}

Date-Based Searches

// Get emails from last week
{
  "tool": "gmail_search_by_date",
  "args": {
    "after": "2024/06/15",
    "before": "2024/06/22",
    "additionalQuery": "has:attachment"
  }
}

Thread Management

// Get a complete conversation
{
  "tool": "gmail_get_thread",
  "args": {
    "threadId": "18f5c3a2b8e9d6f1"
  }
}

Batch Operations

// Get multiple messages at once
{
  "tool": "gmail_batch_get_messages",
  "args": {
    "messageIds": ["msg1", "msg2", "msg3", "msg4", "msg5"],
    "format": "full"
  }
}

Gmail Query Syntax Reference

Common search operators:

• from:sender@example.com - From specific sender
• to:recipient@example.com - To specific recipient
• subject:keyword - Subject contains keyword
• is:unread - Unread messages
• is:important - Marked as important
• has:attachment - Has attachments
• larger:5M - Larger than 5MB
• smaller:1M - Smaller than 1MB
• after:2024/1/1 - After date
• before:2024/12/31 - Before date
• label:work - Has specific label
• in:inbox - In inbox
• in:sent - In sent mail
• in:drafts - In drafts
• in:spam - In spam
• in:trash - In trash

Combine with AND/OR:

• from:user@example.com AND is:unread
• subject:"Project Update" OR subject:"Status Report"
• has:attachment -from:noreply@example.com (NOT from)

Error Handling

The server provides detailed error messages:

• Authentication errors: Invalid or expired tokens
• Permission errors: Missing OAuth scopes
• Not found errors: Invalid message/thread IDs
• Rate limiting: Automatic retry recommendations
• Validation errors: Invalid parameters

Rate Limiting

Gmail API quotas:

• Per-user rate limit: 250 quota units per user per second
• Daily quota: 1 billion quota units per day

The server handles rate limiting gracefully and provides clear error messages when limits are exceeded.

Testing

Local Development Testing

# 1. Install dependencies
cd mcp-gmail
npm install

# 2. Build the server
npm run build

# 3. Set your credentials
export GMAIL_CLIENT_ID="your-client-id"
export GMAIL_CLIENT_SECRET="your-client-secret"
export GMAIL_REFRESH_TOKEN="your-refresh-token"

# 4. Add server locally for testing
claude mcp add gmail-test -s user -- node $(pwd)/dist/index.js

# 5. Start Claude and test
claude
# Try: "Search my Gmail for unread messages"

Limitations (v1.0.0)

This is a read-only server. The following operations are not supported:

• Sending emails
• Modifying messages (mark as read, delete, etc.)
• Creating or modifying labels
• Managing drafts
• Changing message labels

These write operations may be added in future versions.

Security Considerations

• Refresh tokens never expire unless explicitly revoked
• Store credentials securely - anyone with these tokens can read the Gmail account
• Use minimal scopes - this server only requests gmail.readonly
• Revoke access at myaccount.google.com/permissions if needed

Development

Prerequisites

• Node.js 18+
• TypeScript
• Google Cloud project with Gmail API enabled

Setup

git clone <repository>
cd mcp-gmail
npm install
npm run build

Building

npm run build          # Build once
npm run dev           # Build and watch for changes

Contributing

1. Follow the existing code structure and patterns
2. Add comprehensive error handling for new features
3. Update this README with new tools and examples
4. Test thoroughly with real Gmail data
5. Follow the ChillMCP conventions for consistency

License

MIT License - see LICENSE file for details.

Note: This MCP server provides read-only access to Gmail. Always ensure you're using appropriate OAuth scopes and following Google's API usage policies.