Google Workspace MCP Server

Google Workspace MCP Server

A Model Context Protocol server that gives Claude access to Google Workspace — Gmail, Calendar, Drive, Contacts, Sheets, Docs, Slides, Tasks, and 100+ APIs via the gws CLI.

This server powers the Google Workspace connector of DataToRAG, a hosted MCP gateway with per-user OAuth, multi-account support, and Atlassian tools alongside these — add https://datatorag.com/mcp to your MCP client and skip the setup below. Or run this server yourself, standalone or as a Claude Desktop extension.

Tools

| Service | Tools | Operations | |---------|-------|------------| | Gmail | 16 | send, reply, forward, read, search, list, create draft, update draft, send draft, delete draft, mark read, list filters, create filter, delete filter, create label, save attachment to Drive | | Calendar | 6 | list events, get event, create, update, delete, freebusy | | Contacts | 7 | search, get, list, create, update, delete, directory search | | Drive | 3 | search, read file, create folder | | Sheets | 5 | read, update, append, create, delete | | Docs | 5 | get, write, batch update, create, delete | | Slides | 4 | get, create, batch update, delete | | Tasks | 6 | list task lists, list tasks, create, update, complete, delete | | Generic | 1 | gws_run — fallback for any GWS API not covered above | | Auth | 1 | OAuth login and status |

54 tools total. All tools support shared (team) Drives.

Key tool details

gmail_create_draft / gmail_update_draft — Create or replace a Gmail draft. Constructs RFC 2822 MIME messages from structured parameters (to, subject, body, cc, bcc) and base64url-encodes them. gmail_update_draft preserves threading automatically — if no thread_id is provided, it fetches the existing draft's thread ID before replacing the message.

gmail_read — Full MIME payload by default. Pass text_only: true for a compact view (flattened from/to/cc/subject/date, decoded text body with HTML fallback, attachment metadata) that avoids base64 payloads overflowing the response — typically ~2% of the full size. max_body_chars truncates the body with a marker (implies text_only).

gmail_search / gmail_list — Results are flattened to {id, threadId, from, to, subject, date, snippet, labelIds} per message instead of the raw metadata payload.

gmail_send_draft / gmail_delete_draft — Send or permanently delete an existing draft by its draft ID. gmail_send_draft sends a reviewed draft as-is and removes it from Drafts (no orphaned draft left behind), completing the create → review → send loop. gmail_delete_draft deletes immediately (does not move to Trash).

gmail_mark_read — Marks messages as read by removing the UNREAD label. Also supports adding/removing arbitrary labels (STARRED, IMPORTANT, etc.) via add_labels and remove_labels arrays. Pass message_id for a single message, or message_ids (up to 1000) to modify a batch in one API call via users.messages.batchModify. Removes UNREAD by default when no label arrays are given.

gmail_list_filters / gmail_create_filter / gmail_delete_filter / gmail_create_label — Inbox automation: create filters that label, archive, mark-read, or forward matching mail, and create the labels they target. Filter tools need the gmail.settings.basic scope — existing installs must re-authenticate once (gws_auth_setup with action login) to pick it up. Gmail filters are immutable; "editing" one means create new + delete old.

gmail_save_attachment_to_drive — Fetches an attachment from Gmail and uploads it directly to Drive server-side. No base64 data flows through the conversation. Uses async file I/O with guaranteed temp file cleanup via try/finally.

calendar_list_events — Compact view by default: per event you get id, title, times, location, a plain-text description (HTML stripped, truncated at 500 chars, tune with max_description_chars), the organizer, an attendee count plus your own response status, video join links (Meet, or Zoom and friends from conference data), a recurring flag, and attachments. Meetings with 10 or fewer attendees keep their full roster, so a 1:1 still tells you who it's with; larger meetings collapse to the count. Roughly 85% smaller than the raw payload on a busy calendar. Pass full: true for the raw Calendar API response.

calendar_get_event — Full event details with the description converted to plain text. Pass full: true to keep the original HTML.

drive_search — Searches across both personal and shared Drives. Supports full Drive query syntax including folder parents, mimeType filters, and name matching.

drive_create_folder — Creates a folder in Drive, optionally inside a parent folder.

drive_read_file — Reads the text content of any file in Drive by file ID. Routes by mimeType:

• Google Docs → plain text extraction
• Google Sheets → row/column data (A1:Z1000)
• Google Slides → slide structure with placeholder maps and text
• Office formats (.docx, .xlsx, .pptx) → server-side conversion to native Google format, read converted copy, then delete temp copy (guaranteed cleanup via try/finally)
• Plain text / CSV (text/plain, text/csv) → raw content fetch
• Unsupported types (PDF, images, etc.) → returns { error: "Unsupported file type: <mimeType>" }

docs_get — Three modes:

• text (default): plain text with [image:<id>] placeholders for inline images, best for reading/summarizing
• index: text with startIndex/endIndex character positions plus inline object references, use before positional edits
• full: raw API response, for debugging or style operations

All modes include the inlineObjects metadata map (contentUri, size, margins, crop, border) when images are present.

docs_create / sheets_create — Return stripped responses with only essential fields:

• docs_create → { documentId, title }
• sheets_create → { spreadsheetId, title, spreadsheetUrl }

slides_get / slides_create — Return trimmed responses (no masters, layouts, geometry, styling). Each slide includes:

• placeholder_map: maps standard types (TITLE, BODY, SUBTITLE) to objectIds
• elements: all shapes — both standard placeholders and custom text boxes
• Empty placeholders are included so callers can insert text immediately after create without a redundant get call

sheets_read — Returns normalized data:

• columnCount derived from the widest row (handles empty leading rows correctly)
• All rows padded to uniform column count with empty strings

sheets_append — Uses direct Sheets API (spreadsheets.values.append) to preserve 2D array structure. Each inner array becomes a separate row.

docs_write — Uses batchUpdate API with insertText, correctly handles newlines, em dashes, and unicode characters.

gws_run — Fallback tool for any Google Workspace API not covered by the dedicated tools. Accepts service, resource, method, params, and JSON body. Use only when no dedicated tool exists.

Setup (Extension — Claude Desktop)

1. Create a Google Cloud project

Go to Google Cloud Console and create a new project (or use an existing one).

2. Enable Google Workspace APIs

Enable each API you plan to use in your project. Click the links below and hit Enable on each page:

• Gmail API
• Google Calendar API
• Google Drive API
• Google Docs API
• Google Sheets API
• Google Slides API
• People API (for contacts)
• Tasks API

3. Configure OAuth consent screen

Go to OAuth consent screen:

1. Select External user type
2. Fill in the app name (e.g. "Google Workspace CLI") and your email
3. Save and continue through all screens
4. Under Test users, click Add users and add your Google account email

4. Create OAuth credentials

Go to Credentials:

1. Click Create Credentials → OAuth client ID
2. Application type: Desktop app
3. Click Create
4. Copy the Client ID and Client Secret

5. Configure OAuth credentials

cp .env.example .env

Open .env and fill in your Client ID and Client Secret from the previous step.

6. Build the extension

pnpm install
pnpm run build
pnpm run build:extension

This produces google-workspace-mcp.mcpb.

7. Install in Claude Desktop

Open Claude Desktop → Settings → Extensions → Install from file → select google-workspace-mcp.mcpb.

When the extension loads for the first time, a browser window opens automatically for Google OAuth login. Sign in and authorize the app. After that, all tools are ready to use.

Note: If your app is in testing mode (unverified), you'll see a "Google hasn't verified this app" warning. Click Advanced → Go to \<app name\> (unsafe) to proceed. This is safe for personal use.

Setup (HTTP Server — Claude Code / standalone)

1. Complete steps 1–5 above

2. Install and build

pnpm install
pnpm run build

3. Authenticate

With the env vars from step 5 set, run:

./bin/gws-aarch64-apple-darwin/gws auth login -s drive,gmail,sheets,calendar,docs,slides,people,tasks

4. Start the server

node server/index.js

The MCP server starts on http://localhost:39147/mcp (override with PORT env var).

5. Connect Claude Code

claude mcp add google-workspace --transport http http://localhost:39147/mcp

Or add to Claude Desktop MCP config:

{
  "mcpServers": {
    "google-workspace": {
      "type": "streamable-http",
      "url": "http://localhost:39147/mcp"
    }
  }
}

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | PORT | 39147 | HTTP server port | | GWS_OAUTH_CLIENT_ID | — | OAuth client ID | | GWS_OAUTH_CLIENT_SECRET | — | OAuth client secret |

Architecture

src/
├── create-server.ts      # Shared MCP server factory (accepts optional per-session client)
├── extension.ts          # Stdio entry point (.mcpb extension, auto-auth on startup)
├── index.ts              # HTTP entry point (StreamableHTTP, /health + /mcp endpoints)
├── gws-client.ts         # Wrapper around the gws CLI binary, DEFAULT_SERVICES constant
└── tools/
    ├── response.ts       # Response helpers (JSON formatting, 900KB truncation)
    ├── auth.ts           # OAuth login (browser-based, no gcloud needed)
    ├── gmail.ts          # Gmail tools (drafts, mark read, attachments to Drive)
    ├── calendar.ts       # Calendar tools
    ├── contacts.ts       # Contacts / People API tools
    ├── drive.ts          # Drive tools (search, read file, create folder)
    ├── sheets.ts         # Sheets tools (normalized reads, direct API append)
    ├── docs.ts           # Docs tools (text/index/full modes, inline image metadata)
    ├── slides.ts         # Slides tools (trimmed responses, placeholder maps)
    ├── tasks.ts          # Google Tasks tools (lists, CRUD, complete)
    ├── generic.ts        # Generic gws_run fallback
    └── index.ts          # Tool registry (flat Map<name, handler>)

The server wraps the gws CLI binary, which handles OAuth token management and API discovery. Each tool either uses client.helper() for high-level CLI commands or client.api() for direct Google API calls.

The extension (extension.ts) runs via stdio for Claude Desktop .mcpb bundles. The HTTP server (index.ts) runs as a standalone process for Claude Code or other MCP clients. Both share the same createMcpServer() factory.

Key implementation details

• Shared Drive support: All Drive API calls include supportsAllDrives: true (and includeItemsFromAllDrives: true for list operations) so files on team Drives are accessible
• Sandbox compatibility: Sets cwd: os.tmpdir() and GOOGLE_WORKSPACE_CLI_CONFIG_DIR for Claude Desktop's read-only filesystem
• OAuth credentials: Reads from env vars, falls back to bundled oauth.json (injected at build time by scripts/build-extension.sh)
• Auto-auth: Extension checks auth status and scope coverage on startup, opens browser for OAuth login if needed (non-blocking — MCP server starts immediately)
• X-User-Token support: HTTP server accepts X-User-Token header to create per-session clients with pre-obtained access tokens (via GOOGLE_WORKSPACE_CLI_TOKEN env var)
• Response truncation: All responses capped at 900KB to stay within context limits
• Context optimization: docs_get, slides_get, and sheets_read aggressively strip metadata to minimize context usage. docs_get text mode reduces ~50KB API responses to ~2-3KB. slides_get strips masters/layouts/geometry/styling. sheets_read uses the values-only API endpoint.
• Inline image metadata: docs_get includes inlineObjects map with image metadata (contentUri, size, margins) without embedding actual image bytes
• Slides trimming: Strips masters, layouts, geometry, and styling from API responses — returns only objectIds, placeholder types, and text content
• Office file reading: drive_read_file copies Office files with explicit target mimeType to trigger server-side conversion, reads the native copy, then deletes it (guaranteed cleanup via try/finally)
• Unsupported type guard: drive_read_file only fetches raw content for text/plain and text/csv — all other non-native types return a clean error instead of binary data
• Platform support: macOS (arm64, x64), Linux (x64), Windows (x64)

Development

pnpm run dev    # Watch mode — recompiles on change

License

MIT