Connect your own MCP servers

Extension on by default Experimental

Local MCP connects Glean Tau to MCP servers you configure yourself, either a command that runs on your computer or a server at a remote URL. The agent can then use that server's tools in your chats, alongside its Glean tools.

Use Local MCP for tools that Glean doesn't already provide, such as a server you built for your own workflow or a developer tool that runs locally.

warning

Add only servers you trust. A server you add can read the files and credentials you give it, and its tools act on your behalf.

Check Glean first

Before you add a server, check Connected apps in Glean. Glean may already provide the MCP server you need, with your organization's permissions and security controls built in. For how Glean's own MCP servers compare with local ones, see MCP Security, Data Flow, and Permissions.

Add a server

1

Open Local MCP settings

Go to Settings → Extensions → Local MCP, then select Add server.

2

Name the server

Enter a Name. Use letters, numbers, periods, hyphens, or underscores.

3

Choose a connection

Choose how Glean Tau reaches the server:

• Local command runs the server on your computer. It's available only on macOS. Enter the Command, and optionally Arguments (one per line), a Working directory (optional), and Environment (KEY=VALUE per line).
• Remote URL connects to a server over HTTP or HTTPS. Enter the Remote server URL. On Windows, use this option.

4

Test and save

Select Test connection to check that Glean Tau can reach the server, then select Save server.

5

Sign in, if the server asks

If a remote server shows Authentication required, select Authenticate and finish signing in through your browser.

The server appears under Configured servers. Its tools are available in new chats. To use them, ask for the task in a chat, and the agent finds the right tool.

Manage servers

Under Configured servers, use the Enabled switch to turn a server on or off without removing it. Select More actions on a server to Edit, Reconnect, Re-authenticate, or Remove server.

Glean Tau saves your server list in ~/.glean/extensions/glean.local-mcp/servers.json. Sign-in tokens for remote servers are stored in your operating system's keychain, not in that file.

How Glean Tau keeps servers contained

• Approval modes still apply. Registering a server doesn't make its tools trusted. Glean Tau reviews each tool call under your approval mode, the same as other actions. See Agent approval modes.
• Local command servers run in a macOS sandbox. The sandbox limits writes to the server's working directory and any extra paths in its configuration. If the sandbox can't be applied, the server doesn't start.
• Credentials stay explicit. A local server receives only the environment variables you configure for it, not the credentials in your own shell.

Remote servers and local servers that are already running aren't sandboxed by Glean Tau. A tool-call approval doesn't confine them.

Limitations

• Experimental. Behavior and settings may change.
• Local command servers are macOS only. On Windows, a local command server fails to start with "This app cannot enforce the required security restrictions." Use a Remote URL server instead.
• Changes apply to new chats. A chat that's already open keeps the tools it started with.
• Your organization can turn it off. If your admin manages the extension, its toggle shows Managed by your organization.

See also

• Extensions — the full list of extensions and their default states