clay-mcp-bridge

Native Messaging Host for the Clay Chrome Extension. Bridges local MCP (Model Context Protocol) servers to Clay running on a remote machine.

When do I need this?

If you access Clay from a remote server (not localhost), this bridge lets your Mates use MCP servers running on your local machine (GitHub, Notion, Slack, databases, etc.).

If Clay runs on localhost, you don't need this. Clay manages MCP processes directly.

Install

npx clay-mcp-bridge install <extension-id>

Find your extension ID at chrome://extensions (look for "Clay").

Supports Chrome, Arc, and Chromium on macOS and Linux. No sudo required.

Uninstall

npx clay-mcp-bridge uninstall

How it works

Clay Server (remote)
  |  WebSocket
Clay Webapp (your browser)
  |  window.postMessage
Chrome Extension (content script + service worker)
  |  Chrome Native Messaging
clay-mcp-bridge (this package, on your machine)
  |  stdin/stdout
MCP Server processes (GitHub, Notion, etc.)

The bridge reads your MCP config from ~/.clay/mcp.json, spawns stdio-based MCP server processes, and relays JSON-RPC messages between the Chrome Extension and those processes.

Config

The bridge uses ~/.clay/mcp.json:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_TOKEN": "ghp_xxx" }
    }
  },
  "include": [
    "~/.claude/claude_desktop_config.json"
  ]
}

You can manage this config from the Clay Chrome Extension popup (add/remove servers, import existing configs).

The include array merges servers from other config files (Claude Desktop, Cursor, etc.) so you don't have to duplicate settings.

Requirements

• Node.js 18+
• Clay Chrome Extension installed
• A Chromium-based browser (Chrome, Arc, Chromium)

License

MIT