chrome-webstore-mcp

An MCP server that lets your agent (Cursor, Claude, and others) read Chrome Web Store metrics for your extension: installs, uninstalls, active users, impressions, and page views. It is read-only.

You need your own Google Cloud app. Setup takes about 10 minutes and only has to be done once.

1. Create a Google Cloud app

1. Open the Google Cloud Console and create a project. An existing one also works.

2. Search the console for Chrome Web Store API and click Enable.

3. Open Google Auth Platform (called OAuth consent screen in the older interface).

   • In Branding, enter an app name and contact emails.

   • In Audience, choose External.

   • Also in Audience, add the Google account that owns the extension to Test users.

4. In Clients, click Create client and choose Desktop app. It has to be Desktop: this type needs no redirect URI.

5. Copy the Client ID and Client secret.

While the app is in Testing status, Google revokes the sign-in about every 7 days. To avoid this, click Publish app in Audience. If sign-in then shows an unverified app warning, click Advanced and continue: it is your own app. Personal use does not require Google's app verification.

Related MCP server: yourtraffic

2. Find your publisher ID and extension ID

Open the extension in the Developer Dashboard. The page address looks like this:

https://chrome.google.com/webstore/devconsole/<publisher-id>/<extension-id>/...

Take the publisher ID from this address. If you have several publishers, the ID of another one results in a 403 error.

3. Add the server to your MCP config

Only the app credentials are required in the config:

{
  "mcpServers": {
    "chrome-webstore": {
      "command": "npx",
      "args": ["-y", "chrome-webstore-mcp"],
      "env": {
        "CWS_CLIENT_ID": "<client id>",
        "CWS_CLIENT_SECRET": "<client secret>"
      }
    }
  }
}

You can give the agent the publisher ID and extension ID in each request. If you work with one extension, add them to env as defaults so you don't have to repeat them:

"CWS_PUBLISHER_ID": "<publisher id>",
"CWS_EXTENSION_ID": "<extension id>"

IDs from a request take priority over the config.

Where the config lives:

• Cursor: ~/.cursor/mcp.json.

• Claude Code: the claude mcp add command.

Node.js 20 or newer is required.

If a client on Windows cannot start npx, use "command": "cmd" and "args": ["/c", "npx", "-y", "chrome-webstore-mcp"].

The config holds a secret, so use the global file rather than one inside a repository. If the config does live in a project, don't commit it, and pass the secret through an environment variable. In Cursor that looks like "CWS_CLIENT_SECRET": "${env:CWS_CLIENT_SECRET}".

4. Ask your agent for metrics

For example: "Show installs and uninstalls for October". If the IDs are not in the config, include them: "Show October installs for extension <extension id>, publisher <publisher id>".

The first request needs a Google sign-in with the account that owns the extension. The same happens automatically if the sign-in expires. How it looks depends on the client:

• If the client supports URL elicitation, it asks to open the sign-in page itself, and the agent gets the data right after you sign in.

• Otherwise the server opens your browser and gives the agent a link. After signing in, ask the agent to repeat the request. Cursor currently works this way.

A sign-in button in the client's settings, as remote servers have, is not available for local stdio servers.

The token is stored in ~/.config/chrome-webstore-mcp/token.json with 0600 permissions and is sent only to Google. On Windows the file is %USERPROFILE%\.config\chrome-webstore-mcp\token.json, which has no 0600 mode and relies on the permissions of your profile folder.

To sign out, delete the token file and restart the server.

The query_metrics tool

Data arrives with a delay of about two days.

The sign-in is shared across the whole server, so the signed-in account must have access to every extension you request. For publishers in different Google accounts, add a separate server for each one and give each its own XDG_CONFIG_HOME, which keeps their tokens apart.

Troubleshooting

License

MIT