#!/usr/bin/env node
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { createSigner } from "x402-fetch";
import { z } from "zod";
import { ServerPaymentClient } from "./payment.js";
import { Connection, LAMPORTS_PER_SOL, Keypair } from "@solana/web3.js";
import bs58 from 'bs58';
interface PaymentRecord {
url: string;
amount: number;
recipient: string;
timestamp: string;
signature: string;
}
let paymentHistory: PaymentRecord[] = [];
let paymentLimit: number | null = null;
// Create server instance
const server = new McpServer({
name: "X402 Payment MCP Server",
version: "1.0.0",
});
// Get wallet balance
server.registerTool(
"get-balance",
{
title: "Get Wallet Balance",
description: "Check the current SOL balance in your wallet",
inputSchema: {},
},
async () => {
try {
const signer = await createSigner("solana-devnet", process.env.SOLANA_PRIVATE_KEY || " ");
const connection = new Connection("https://api.devnet.solana.com", "confirmed");
const privateKeyBytes = bs58.decode(process.env.SOLANA_PRIVATE_KEY || "");
const keypair = Keypair.fromSecretKey(privateKeyBytes);
const publicKey = keypair.publicKey;
const balance = await connection.getBalance(publicKey);
const solBalance = balance / LAMPORTS_PER_SOL;
return {
content: [{
type: "text",
text: JSON.stringify({
balance: solBalance,
unit: "SOL",
network: "devnet",
address: publicKey
}, null, 2)
}]
};
} catch (err: any) {
return {
content: [{
type: "text",
text: `Error: ${err.message || "Failed to get balance"}`
}],
isError: true
};
}
}
);
// Get payment history
server.registerTool(
"get-payment-history",
{
title: "Get Payment History",
description: "View all payments made during this session",
inputSchema: {
limit: z.number().optional().describe("Maximum number of records to return (default: all)")
},
},
async ({ limit }) => {
try {
const records = limit ? paymentHistory.slice(-limit) : paymentHistory;
return {
content: [{
type: "text",
text: JSON.stringify({
total_payments: paymentHistory.length,
records: records,
total_spent: paymentHistory.reduce((sum, r) => sum + r.amount, 0)
}, null, 2)
}]
};
} catch (err: any) {
return {
content: [{
type: "text",
text: `Error: ${err.message || "Failed to get payment history"}`
}],
isError: true
};
}
}
);
// Set payment limit
server.registerTool(
"set-payment-limit",
{
title: "Set Payment Limit",
description: "Set maximum amount willing to pay per request (in SOL). Set to 0 to remove limit.",
inputSchema: {
limit: z.number().describe("Maximum payment amount in SOL (0 to remove limit)")
},
},
async ({ limit }) => {
try {
if (limit < 0) {
throw new Error("Limit must be non-negative");
}
paymentLimit = limit === 0 ? null : limit;
return {
content: [{
type: "text",
text: JSON.stringify({
message: paymentLimit === null
? "Payment limit removed"
: `Payment limit set to ${paymentLimit} SOL`,
current_limit: paymentLimit
}, null, 2)
}]
};
} catch (err: any) {
return {
content: [{
type: "text",
text: `Error: ${err.message || "Failed to set payment limit"}`
}],
isError: true
};
}
}
);
// Modified fetch-with-payment to track payments and enforce limits
server.registerTool(
"fetch-with-payment",
{
title: "Fetch Data",
description: "Fetch data from a website or API. Automatically handles payment if required (402 status).",
inputSchema: {
url: z.string().describe("The URL to fetch data from"),
method: z.enum(["GET", "POST"]).optional().describe("HTTP method (default: GET)"),
body: z.string().optional().describe("Request body for POST requests (JSON string)")
},
},
async ({ url, method = "GET", body }) => {
try {
const signer = await createSigner("solana-devnet", process.env.SOLANA_PRIVATE_KEY || " ");
const paymentClient = new ServerPaymentClient({ network: 'solana-devnet', signer });
const options: RequestInit = {
method,
headers: { "Content-Type": "application/json" },
};
if (method === "POST" && body) {
options.body = body;
}
const response = await paymentClient.fetch(url, options);
// Track payment if one was made
const paymentInfo = (paymentClient as any).extractPaymentInfo?.(response);
if (paymentInfo) {
const amountInSol = paymentInfo.amount / LAMPORTS_PER_SOL;
// Check payment limit
if (paymentLimit !== null && amountInSol > paymentLimit) {
throw new Error(`Payment amount (${amountInSol} SOL) exceeds limit (${paymentLimit} SOL)`);
}
paymentHistory.push({
url,
amount: amountInSol,
recipient: paymentInfo.recipient,
timestamp: new Date().toISOString(),
signature: paymentInfo.signature
});
}
const data = await response.json();
return {
content: [{
type: "text",
text: JSON.stringify({
success: true,
data,
payment_made: !!paymentInfo,
payment_amount: paymentInfo ? paymentInfo.amount / LAMPORTS_PER_SOL : 0
})
}]
};
} catch (err: any) {
return {
content: [{
type: "text",
text: `Error: ${err.message || "Request failed"}`
}],
isError: true
};
}
}
);
// Start the server
async function main() {
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("X402 Payment MCP Server running on stdio");
}
main().catch((error) => {
console.error("Fatal error in main():", error);
process.exit(1);
});
