WebMCP Today MCP Bridge

@webmcp-today/mcp-bridge is an MCP server for WebMCP Today: a registry of packages that add WebMCP tools to supported sites through the WebMCP Today browser extension.

It lets an MCP client browse and publish registry packages, manage account-level package pins, and—when the optional local browser bridge is installed—discover and invoke live WebMCP tools in the user's selected browser tab.

Install and configure

Requires Node.js 20 or later. Configure any stdio-capable MCP client to run the package with npx:

{
  "mcpServers": {
    "webmcp-today": {
      "command": "npx",
      "args": ["--yes", "@webmcp-today/[email protected]"]
    }
  }
}

The default registry is https://webmcp.today. Set WEBMCP_TODAY_API_URL only when using another compatible registry endpoint.

Registry API key (optional)

Public package discovery does not need credentials. Set WEBMCP_TODAY_API_KEY in the MCP server environment to use authenticated account and publisher actions, including package pins, publishing, and package metadata updates. Create an API key in WebMCP Today settings; do not put it in prompts, package definitions, or source control.

{
  "mcpServers": {
    "webmcp-today": {
      "command": "npx",
      "args": ["--yes", "@webmcp-today/[email protected]"],
      "env": {
        "WEBMCP_TODAY_API_KEY": "<your-api-key>"
      }
    }
  }
}

Capabilities

The server provides tools in these categories:

• Registry discovery — look up packages for a URL, browse packages, retrieve a package at its latest version, and view registry statistics.
• Account and publishing — inspect and manage account-level package pins; publish packages and append versions; update package metadata. These actions require an API key. An account pin does not install a package in the browser; the returned install link hands that explicit browser-consent step to the user.
• Live WebMCP bridge — list and focus the user-selected visible Chrome or Brave tab, list its live tools, and execute a selected tool using the document and tool-list generations returned by discovery.
• Bridge administration — install, inspect, and remove the first-party native bridge on supported macOS browsers.

Live browser bridge

The live bridge is optional. It requires the WebMCP Today extension and the first-party native host setup on macOS Chrome or Brave. After configuring the MCP server, call setup_webmcp_bridge with explicit approval, for example:

{ "browser": "chrome", "confirm": true }

Setup copies the bundled native host under ~/.config/webmcp-today and writes only this bridge's native-messaging manifest(s) in the browser's Application Support directories. Brave writes both its own manifest and a Chrome-compatibility manifest. It runs under Node 20 or later or Bun. Use get_webmcp_bridge_status to inspect the installation without exposing the bridge secret.

The bridge only operates on the user-selected active, visible Chrome or Brave tab. It does not enable WebMCP, run arbitrary JavaScript, proxy Chrome DevTools Protocol, or expose an HTTP port. Registry-injected tools make same-origin page requests with the page's authenticated cookies, so they can act as the signed-in site account. A page can still refuse injected WebMCP tools, and changing a page or its tools between discovery and execution requires discovery again.

The extension's local fallback can serve tools through this bridge without the current WebMCP testing flag. That flag is still required for Chrome's native agent to see injected tools in the current browser preview.

Confirmations and retries

• Registry-injected tools marked as destructive retain their page-level window.confirm prompt; approve it in the selected tab.
• setup_webmcp_bridge and uninstall_webmcp_bridge make no filesystem changes until called with confirm: true.
• On execution-timeout, the browser may have completed the tool call: verify the result before retrying. dispatch-failed means the call was not dispatched and can be retried.
• Removing a Brave installation intentionally leaves its Chrome compatibility manifest. Follow the tool's reported instruction to run the confirmed Chrome uninstall after closing both browsers before treating the bridge as fully removed.

Development

For repository development, install dependencies and run the package tests:

bun install
bun run --filter @webmcp-today/mcp-bridge test

Links

• WebMCP Today
• Source code
• Issues
• MIT License