# PaidMCP - Charge Bitcoin For MCP Server Tools

Receive lightning payments for each tool request, powered by [NWC](https://nwc.dev).

In a few lines of code, turn your [modelcontextprotocol/sdk](https://github.com/modelcontextprotocol/typescript-sdk) MCP Server tool into a paid tool:

```diff
- const server = new McpServer({name: "your-mcp-server"});
+ const server = new PaidMcpServer({name: "your mcp server"}, {nwcUrl});
- server.registerTool(name, config, callback);
+ server.registerPaidTool(name, config, charge, callback);
```

## Get started

### Install

```bash
npm install @getalby/paidmcp
```

or

```bash
yarn add @getalby/paidmcp
```

### Import and use `PaidMcpServer`

`PaidMcpServer` is a thin wrapper around the standard `McpServer` class that adds ability to create paid tools.

> This MCP requires an NWC-enabled lightning wallet to be able to charge payments. [NWC](https://nwc.dev) is an open protocol for connecting apps to lightning wallets. If you don't have a NWC-enabled lightning wallet yet, try [Alby Hub](https://albyhub.com).

```js
import { PaidMcpServer } from "@getalby/paidmcp";

// Configure your NWC URL - should be "nostr+walletconnect://..."
const nwcUrl = process.env.NWC_URL;
// use PaidMcpServer instead of McpServer
const server = new PaidMcpServer({ name: "your-mcp-server" }, { nwcUrl });

// for paid tools, use registerPaidTool
// it requires an additional argument before the callback
// to configure charging information based on the request
server.registerPaidTool(
  name,
  config,
  (args) => ({ satoshi: 1, description: "Paid tool usage: " + args.city }),
  callback
);
```

## Examples

See [weather example](./examples/weather/README.md)

## How it works

For a simple example we have a paid weather MCP - that you can fetch the weather for a city by paying a small fee.

```json
{
  "city": "Berlin"
}
```

Some additional parameters are injected into the tool request and response. If a paid tool is requested without a payment hash, the following response will be returned:

> the required payment amount and description can be configured per-request.

```json
{
  "payment_instructions": "Payment required. Pay the payment_request and try the same request again with the payment_hash set to continue.",
  "payment_request": "lnbc...",
  "payment_hash": "2b3e38cff2ab0172d28e004931938c09a19b3e81a2054c3b46ac087ec3bc30b3"
}
```

Once the payment is made by the human or their agent (this can be done with [Alby MCP](https://github.com/getAlby/mcp)), the agent will request the same tool again, this time providing the `payment_hash` along with the request:

```json
{
  "city": "Berlin",
  "payment_hash": "2b3e38cff2ab0172d28e004931938c09a19b3e81a2054c3b46ac087ec3bc30b3"
}
```

The MCP server will then execute the actual tool callback as normal.

```json
{
  "temperature_celcius": "27.4"
}
```