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Introducing x402-mcp, a library that integrates with the AI SDK to bring x402 paywalls to Model Context Protocol (MCP) servers to let agents discover and call pay for MCP tools easily and securely.
With x402-mcp, you can define MCP servers with paidTools that require payment to run, enabling account-less, low-latency, anonymous payments directly in AI workflows. Payments confirm in ~100–200ms, with fees under $0.01 and support for minimums under $0.001.
Getting started is easy, here's how you can define a paid tool:
import { createPaidMcpHandler } from "x402-mcp";import z from "zod";
const handler = createPaidMcpHandler( (server) => { server.paidTool( "add_numbers", { // declare a price of $0.001 price: 0.001 }, { a: z.number(), b: z.number() }, async (args) => { // ...your tool call } ); }, { recipient: process.env.WALLET_ADDRESS });
export { handler as GET, handler as POST };And integrating with AI SDK MCP Clients takes just one function to enable payments:
import { experimental_createMCPClient as createMCPClient } from "ai";import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";import { withPayment } from "x402-mcp";
const mcpClient = await createMCPClient({ transport: new StreamableHTTPClientTransport(url),}).then((client) => withPayment(client, { account: process.env.PRIVATE_KEY }));
const tools = await mcpClient.tools();Read more about x402 or try our full stack x402 AI Starter Kit.
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