pi-webmcp

A Pi extension that connects Pi to webpages that register WebMCP tools.

[!IMPORTANT]

Both the WebMCP specification and Chrome’s implementation are in active development. Anticipate breaking changes that affect this extension.

[!CAUTION]

This extension can pose a security risk in its default operating mode once the /webmcp command is run. A malicious webpage could poison the running Pi session’s context via its WebMCP tool instructions.

Use at your own risk. Consider setting allowedOrigins to restrict which webpages Pi can connect to.

Demo

First-time Setup

1. Install this extension via npm.

   pi install npm:pi-webmcp
   

2. Enable Chrome remote debugging by visiting chrome://inspect/#remote-debugging.

3. Enable the relevant Chrome flags for WebMCP.

   • chrome://flags/#devtools-webmcp-support
   • chrome://flags/#enable-webmcp-testing

Usage

1. Run /webmcp and accept the once-per-session confirmation prompt in Chrome.

2. Navigate to a WebMCP-capable page, such as Chrome Lab’s WebMCP Travel demo.

   More can be found here.

Commands

• /webmcp or /webmcp connect — Connect to Chrome and discover WebMCP tools.
• /webmcp disconnect — Disconnect from Chrome WebMCP.
• /webmcp list — Show active WebMCP tools.

Options

Configure WebMCP options under the webmcp key in Pi settings, either globally in ~/.pi/agent/settings.json or per trusted project in .pi/settings.json:

{
  "webmcp": {
    "allowedOrigins": ["googlechromelabs.github.io"]
  }
}

Option	Description
webmcp.allowedOrigins	When specified, Pi will only discover and connect to WebMCP tools from these origins.
webmcp.disallowedOrigins	When specified, Pi will not discover or connect to WebMCP tools from these origins.
webmcp.cdp	Custom Chrome DevTools Protocol port or browser websocket URL to connect to.

Browser Support

WebMCP is currently only implemented in Chrome, so this extension is scoped to Chromium-based browsers for now. We plan to support additional browsers if / when they implement WebMCP.