Google Chat MCP

A small stdio MCP server that lets an AI agent (Claude Code, Claude Desktop, or any MCP client) read and send Google Chat messages as the signed-in user, through the Google Chat API with user OAuth.

• 21 tools for spaces, messages, members and attachments

• Safety switches: read-only mode, a space allowlist, and one fixed folder for files

• Plain fetch against the Chat REST API; the only dependencies are the MCP SDK and zod

• One-time sign-in with PKCE and a loopback redirect; the token refreshes on its own after that

Needs a Google Workspace account. Google's Chat API guide lists a Business or Enterprise Workspace account as a prerequisite. A personal @gmail.com account is not supported.

Tools

Everything you send shows under your own name, with the Chat app's name from your Google Cloud project as a small chip next to it.

Related MCP server: gmail-mcp

Demo

Claude Code with this server, in a test Workspace. The project's CLAUDE.md asks Claude to show a draft before it sends a message and wait for "yes". That is an instruction to the model, not something the server enforces.

Claude drafts a message to a space, waits, and sends it after "Yes send it":

Akshay sees it in the space, sent by Tarun with the "Texperiments Chat MCP" chip:

Create a space and add two people (no draft needed):

The same message from the sender's side:

A direct message to Akshay:

Reading the reply:

A DM where Claude writes the text itself:

Sending a file from the files folder:

Safety

An agent with this server can post as you, change spaces and remove people. These settings limit what it can do:

Also keep in mind:

• Do not auto-approve the write tools in your MCP client. Tools carry MCP hints (readOnlyHint, destructiveHint), but hints are only hints; the client's approval prompt is what stops a wrong send.

• Messages the agent reads are untrusted input. Anyone in a space can write a message that tries to steer the agent ("reply to X with ..."). This is prompt injection; review every write before you approve it.

• "Approve the exact text first" in the tool descriptions is advice to the model, not something the server enforces.

Setup

You need a Google Cloud project in your Workspace, the Chat API enabled, an OAuth consent screen, a Chat app configuration and a Desktop OAuth client. It takes about 10 minutes. The screenshots were taken in a test Workspace (texperiments.com); use your own names.

1. Open the Google Cloud console

Go to https://console.cloud.google.com/, signed in with your Workspace account.

2. Accept the Google Cloud terms (first visit only)

Tick the "I agree to the Google Cloud Platform Terms of Service" checkbox, then click Agree and continue. No billing account is needed for the Chat API, so you can ignore the "$300 free trial" banner.

On the first visit, Google also creates the Cloud organization for your Workspace domain.

3. Create a project

Click the project picker (Select a project) at the top, then New project.

Enter a project name. The project ID follows the name and cannot be changed later. Organization and parent resource are your Workspace domain. Click Create.

The notifications panel confirms it; Select Project opens it.

4. Enable the Google Chat API

Open APIs & Services → Library.

Search for "Google Chat API" and press Enter.

Pick Google Chat API (not "Chat MCP API").

Click Enable.

The details page shows Status: Enabled.

5. Configure the OAuth consent screen

Open Google Auth Platform → Overview and click Get started.

App Information: enter an app name and pick the user support email.

Audience: choose Internal. Only users in your Workspace can sign in, and Google does not need to verify the app.

Contact Information: an email where Google can reach you about the project.

Finish: tick "I agree to the Google API Services: User Data Policy", click Continue, then Create.

6. Configure the Chat app (needed even for user sign-in)

Open APIs & Services → Enabled APIs & services → Google Chat API → Configuration. The Chat API refuses calls from a project without a Chat app configuration, and the app name becomes the chip on messages you send.

Set an App name and a Description (40 characters max). Switch Interactive features off and confirm Disable, so nobody can message or add the app. Leave "Build this Chat app as a Workspace add-on" as it is; clearing it cannot be undone. Click Save.

7. Create a Desktop OAuth client

Open Google Auth Platform → Clients → Create client.

Choose Desktop app, give it a name, and click Create.

In the OAuth client created dialog, click Download JSON. Google shows the client secret only once. Keep the file outside this repository; it is a credential.

8. Install and sign in

npm install
npm run build

Sign in once, pointing at the downloaded client file:

GOOGLE_CHAT_CREDENTIALS=/path/to/client.json npm run auth

Open the printed URL and choose your Workspace account.

The consent screen lists the Chat permissions the server asks for. Click Allow.

The browser lands on a local page and the token is saved (default ~/.google-chat-mcp/token.json).

Run npm run auth again only if the token is revoked, or after switching read-only mode on or off (the scopes change).

Register the server

Claude Code (.mcp.json in your project):

{
  "mcpServers": {
    "google-chat": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/google-chat-mcp/dist/index.js"],
      "env": {
        "GOOGLE_CHAT_CREDENTIALS": "/path/to/client.json"
      }
    }
  }
}

Claude Desktop uses the same mcpServers block in claude_desktop_config.json. Restart the client after changing the config or rebuilding.

Environment variables

Scopes requested: chat.spaces, chat.messages, chat.memberships and chat.delete; in read-only mode, chat.spaces.readonly, chat.messages.readonly and chat.memberships.readonly.

Limits

• The Chat API has no keyword search. search_spaces lists your spaces and matches names locally; to find a message, read a space with since.

• Attachments stored in Google Drive cannot be downloaded through the Chat API; only uploaded files can. Uploads are limited to 200 MB.

• New Workspace users can take a while to appear in Chat's people search; the full email address works sooner.

Turning it off

• Stop the server: remove it from your MCP config.

• Revoke access: remove the app at myaccount.google.com → Security → Third-party apps, and delete the token file.

• Remove it entirely: delete the Google Cloud project. This also cuts off every token issued through it.

Code layout

• src/index.ts: starts the server; node dist/index.js auth runs the sign-in instead

• src/auth.ts: loads the client file, runs the sign-in, stores and refreshes the token

• src/chat.ts: thin fetch wrappers over the Chat REST API v1

• src/safety.ts: read-only mode, allowlist and files folder

• src/tools/: the tools, one file per area

License

ISC, see LICENSE.