# ChatGPT MCP Server Template

A boilerplate repository for building a local Node.js Model Context Protocol (MCP) Server that integrates seamlessly with the **ChatGPT Web UI**.

## 🌟 Features
- **Express + MCP SDK**: Utilizes the official `@modelcontextprotocol/sdk` with Server-Sent Events (SSE).
- **Mock OAuth with DCR**: Automatically bypasses ChatGPT's strict remote MCP OAuth requirements by implementing a mock OAuth flow and Dynamic Client Registration (DCR). No need to manually enter Client IDs!
- **Tunnel Ready**: Includes npm scripts to instantly expose your local server securely over HTTPS via `Pinggy`.

## 🚀 Getting Started

### 1. Install Dependencies
```bash
npm install
```

### 2. Run the Server
Start the local server in development mode:
```bash
npm run dev
```

### 3. Expose the Server to the Internet
In a separate terminal, run the following command to start a free, stable SSH tunnel via Pinggy:
```bash
npm run tunnel
```
You will receive an output containing a URL like: `https://<hash>.run.pinggy-free.link`.

### 4. Connect to ChatGPT
1. Go to **Settings > Custom Tools / MCP Servers** in ChatGPT.
2. Under **MCP Server URL**, enter your Pinggy URL appended with `/sse`:
   `https://<hash>.run.pinggy-free.link/sse`
3. Under **Authentication**, select `OAuth`.
4. Click Save. ChatGPT will auto-register and authenticate instantly!

## 🛠️ Adding Custom Tools

To add your own tools, database queries, or local API integrations, edit `src/tools/example.ts`.

## ⚠️ Security Warning

This template mocks the OAuth flow and implicitly grants access to any client that connects. **Do not expose highly sensitive local operations** without adding your own authorization checks in the tool handlers, or ensure you configure ChatGPT to "Ask before running" for mutating operations.

## 🐛 Troubleshooting

### Why not use `localtunnel`?
If you try to substitute Pinggy with `localtunnel` (e.g. `npx localtunnel --port 3000`), ChatGPT will fail to connect with an error like:
`The server doesn't support RFC 7591 Dynamic Client Registration`
**Reason**: `localtunnel` injects a "Click to Continue" HTML warning page on the first visit. This intercepts the `.well-known` JSON endpoints required by ChatGPT for OAuth Discovery, breaking the authentication flow. Pinggy is used in this template because it streams traffic directly without injecting warning pages.