feat: add payments-mcp

Author: mempirate

README.md

@@ -32,6 +32,13 @@ pnpm dev
 npx @modelcontextprotocol/inspector
 ```
 
+## Development
+Run the following command in the `packages/payments-mcp` directory:
+```bash
+pnpm link
+```
+You'll now be able to run `payments-mcp` anywhere (e.g. in Claude Desktop MCP).
+
 ## Deploy
 ```bash
 fly secrets set RPC_URL=$RPC_URL

packages/payments-mcp/package.json

@@ -5,6 +5,9 @@
   "type": "module",
   "main": "dist/index.js",
   "private": true,
+  "bin": {
+    "payments-mcp": "./dist/index.js"
+  },
   "scripts": {
     "build": "tsc",
     "dev": "tsx watch src/index.ts",

packages/payments-mcp/src/index.ts

@@ -1,100 +1,98 @@
+#!/usr/bin/env node
+
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import { z } from 'zod';
 import {
-  createWalletClient,
-  http,
-  isAddress,
-  type Account,
-  type Hex,
+    createWalletClient,
+    http,
+    isAddress,
+    type Hex,
 } from 'viem';
 import { privateKeyToAccount } from 'viem/accounts';
 import {
-  createPaymentHeader,
-  selectPaymentRequirements,
-} from 'x402/dist/esm/client/index.mjs';
+    createPaymentHeader,
+} from 'x402/client';
 import debug from 'debug';
 
 import pkg from '../package.json' with { type: 'json' };
 import { base } from 'viem/chains';
 
 const X402_VERSION = 1;
+const BASE_USDC_ADDRESS = '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913';
 
 // Load the environment variables
 const PRIVATE_KEY = process.env.PRIVATE_KEY as Hex;
 const MAX_PAYMENT_AMOUNT_USDC = process.env.MAX_PAYMENT_AMOUNT_USDC;
 
 if (!PRIVATE_KEY) {
-  throw new Error('PRIVATE_KEY is not set');
+    throw new Error('PRIVATE_KEY is not set');
 }
 
 if (!MAX_PAYMENT_AMOUNT_USDC) {
-  throw new Error('MAX_PAYMENT_AMOUNT_USDC is not set');
+    throw new Error('MAX_PAYMENT_AMOUNT_USDC is not set');
 }
 
 const log = debug('payments-mcp');
 
 const walletClient = createWalletClient({
-  chain: base,
-  transport: http(),
-  account: privateKeyToAccount(PRIVATE_KEY),
+    chain: base,
+    transport: http(),
+    account: privateKeyToAccount(PRIVATE_KEY),
 });
 
 const server = new McpServer({
-  name: pkg.name,
-  version: pkg.version,
+    name: pkg.name,
+    version: pkg.version,
 });
 
 server.tool(
-  'create_payment',
-  'Create a payment to use with paid MCP servers.',
-  {
-    tool: z.string().describe('The MCP tool to pay for'),
-    amount: z
-      .number()
-      .max(Number(MAX_PAYMENT_AMOUNT_USDC))
-      .describe('The payment amount in USDC'),
-    asset: z
-      .string()
-      .refine(isAddress, { message: 'Invalid address' })
-      .describe('The asset to pay with'),
-    recipient: z
-      .string()
-      .refine(isAddress, { message: 'Invalid address' })
-      .describe('The recipient of the payment'),
-  },
-  async ({ amount, asset, recipient, tool }) => {
-    log(`Creating payment of ${amount} ${asset} to ${recipient}`);
+    'create_payment',
+    'Create a payment to use with paid MCP servers.',
+    {
+        tool: z.string().describe('The MCP tool to pay for').optional(),
+        amount: z
+            .number()
+            .max(Number(MAX_PAYMENT_AMOUNT_USDC))
+            .describe('The payment amount in USDC'),
+        recipient: z
+            .string()
+            .refine(isAddress, { message: 'Invalid address' })
+            .describe('The recipient of the payment'),
+    },
+    async ({ amount, recipient, tool }) => {
+        log(`Creating payment of ${amount} to ${recipient}`);
 
-    const header = await createPaymentHeader(
-      walletClient as any,
-      X402_VERSION,
-      {
-        scheme: 'exact',
-        description: 'Payment for MCP server',
-        network: 'base',
-        maxAmountRequired: amount.toString(),
-        resource: tool,
-        mimeType: 'application/json',
-        payTo: recipient,
-        maxTimeoutSeconds: 3600,
-        asset,
-      }
-    );
+        const header = await createPaymentHeader(
+            walletClient as any,
+            X402_VERSION,
+            {
+                scheme: 'exact',
+                description: 'Payment for MCP server',
+                network: 'base',
+                maxAmountRequired: amount.toString(),
+                resource: tool ?? 'unknown',
+                mimeType: 'application/json',
+                payTo: recipient,
+                maxTimeoutSeconds: 3600,
+                asset: BASE_USDC_ADDRESS,
+            }
+        );
 
-    log(`Payment header: ${header}`);
+        log(`Payment header: ${header}`);
 
-    return {
-      content: [
-        {
-          type: 'text',
-          text: header,
-        },
-      ],
-    };
-  }
+        return {
+            content: [
+                {
+                    type: 'text',
+                    text: header,
+                },
+            ],
+        };
+    }
 );
 
 const transport = new StdioServerTransport();
 
+log('Starting MCP server transport=stdio');
 await server.connect(transport);

packages/payments-mcp/tsconfig.json

@@ -2,7 +2,9 @@
     "extends": "../../tsconfig.base.json",
     "compilerOptions": {
         "outDir": "./dist",
-        "rootDir": "./src"
+        "rootDir": "./src",
+        "module": "nodenext",
+        "moduleResolution": "nodenext"
     },
     "include": [
         "src/**/*"