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kelvinzer0

mcp-bridge-cf

by kelvinzer0
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MCP Bridge — Dynamic Tool Gateway

A generic bridge between any MCP client and any tool provider via Cloudflare Workers Durable Objects. Each room gets an isolated Durable Object instance. Tool providers connect via WebSocket, MCP clients connect via Streamable HTTP. Tools are registered dynamically and discovered automatically.

How It Works

┌─────────────────┐  WebSocket   ┌──────────────────────┐  HTTP/SSE   ┌──────────────┐
│  Tool Provider  │ ───────────→ │  Cloudflare Worker   │ ──────────→ │  MCP Client  │
│  (Extension,    │              │  (Durable Object)    │             │  (VS Code,   │
│   App, Script)  │  register    │                      │ tools/list  │   Claude,    │
│                 │  tools       │  dynamic registry    │ tools/call  │   Cursor)    │
│  execute        │─────────────→│  + bridge            │───────────→│              │
│  tools          │←─────────────│  forward calls       │←───────────│  AI agent    │
│                 │  callTool    │                      │             │              │
└─────────────────┘              └──────────────────────┘             └──────────────┘

Related MCP server: toolhive-mcp

Quick Start

1. Deploy

git clone https://github.com/kelvinzer0/mcp-bridge-cf
cd mcp-bridge-cf
npm install
npx wrangler login
npm run deploy

2. Create a Room

curl https://mcp-bridge.<subdomain>.workers.dev/new

Response:

{
  "room": "ab1fe4c7",
  "extension_url": "https://mcp-bridge.<subdomain>.workers.dev/ws/extension?room=ab1fe4c7",
  "mcp_url": "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7",
  "health_url": "https://mcp-bridge.<subdomain>.workers.dev/health?room=ab1fe4c7"
}

3. Connect Tool Provider

const { extension_url } = await fetch("https://mcp-bridge.<subdomain>.workers.dev/new").then(r => r.json())
const ws = new WebSocket(extension_url)

// Register tools
ws.send(JSON.stringify({
  type: "registerTools",
  tools: [{ name: "my_tool", description: "...", inputSchema: { ... } }]
}))

// Handle tool calls
ws.onmessage = (event) => {
  const msg = JSON.parse(event.data)
  if (msg.type === "callTool") {
    const result = executeTool(msg.name, msg.params)
    ws.send(JSON.stringify({ type: "toolResult", callId: msg.callId, result }))
  }
}

4. Connect MCP Client

Use the mcp_url from step 2. Setup per client:

OpenCode (opencode.json):

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "browser-bridge": {
      "type": "remote",
      "url": "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7",
      "enabled": true
    }
  }
}

Claude Desktop — Settings → Connectors → Add remote server URL:

https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7

Or claude_desktop_config.json:

{
  "mcpServers": {
    "browser-bridge": {
      "command": "npx",
      "args": ["mcp-remote", "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7"]
    }
  }
}

Cursor (~/.cursor/mcp.json):

{
  "mcpServers": {
    "browser-bridge": {
      "url": "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7"
    }
  }
}

OpenClaw:

openclaw mcp add browser-bridge --url "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7"

Or openclaw.json:

{
  "mcp": {
    "servers": {
      "browser-bridge": {
        "transport": "sse",
        "url": "https://mcp-bridge.<subdomain>.workers.dev/mcp?room=ab1fe4c7"
      }
    }
  }
}

Protocol

Tool Provider → Bridge (WebSocket)

Message

Description

{ type: "registerTools", tools: [...] }

Register tools

{ type: "unregisterTools", names: [...] }

Unregister tools

{ type: "toolResult", callId, result }

Return tool result

{ type: "pong" }

Ping response

Bridge → Tool Provider (WebSocket)

Message

Description

{ type: "callTool", callId, name, params }

Execute tool

{ type: "ping" }

Keepalive

MCP Client → Bridge (Streamable HTTP)

Standard MCP protocol on /mcp?room=<id>:

  • POST /mcp?room=<id> — JSON-RPC (initialize, tools/list, tools/call)

  • GET /mcp?room=<id> — SSE stream

Endpoints

Endpoint

Protocol

Description

/new

HTTP GET

Generate new room

/ws/extension?room=<id>

WebSocket

Tool provider connects here

/mcp?room=<id>

Streamable HTTP

MCP client connects here

/health?room=<id>

HTTP GET

Room status + tool list

Example: Browser Extension

See extension-example/ for a Chrome extension that:

  • Connects to a room via WebSocket

  • Detects page context (GitHub, Gmail, Notion, etc.)

  • Registers context-specific tools dynamically

  • Executes tools in the page DOM

Development

npm run dev      # Local dev with wrangler
npm run typecheck

Security

For production use, add OAuth:

import OAuthProvider from "@cloudflare/workers-oauth-provider"

export default new OAuthProvider({
  apiRoute: "/mcp",
  apiHandler: ...,
})

License

MIT

This server cannot be deployed

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Maintenance

ActivityMaintained
ResponsivenessNo issues

Resources

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