mcp-x402-sdk — Make any MCP server chargeable in 5 lines

The hinge, not the cathedral.
Drop this into your MCP server. Agents pay USDC/RLUSD via x402.
No AgentCards. No credit bureau. No registry join. No worldview required.

npm i @scriptmasterlabs/mcp-x402-sdk

Drop-in

import { x402Payment } from '@scriptmasterlabs/mcp-x402-sdk';
import { z } from 'zod';

server.tool(
  'my_paid_tool',
  { city: z.string() },
  x402Payment({
    price: '0.01',
    currency: 'USDC',
    inputSchema: z.object({ city: z.string() }),
    handler: async (input, receipt) => ({
      content: [{
        type: 'text',
        text: JSON.stringify({ weather: 'sunny', paid: receipt }),
      }],
    }),
  }),
);

That is the whole product for most builders.

| You keep | We handle | |----------|-----------| | Your tools + MCP server | Payment attempt + receipt shape | | Your pricing | USDC / RLUSD, Base default | | Your UX | No mandatory identity format |

What this is NOT

• Not “install our 43-tool mall”
• Not AgentCard / Ed25519 onboarding
• Not a credit-bureau membership
• Not SqueezeOS / Leviathan adoption

Those exist elsewhere. This package is only the charge wrapper.

Env (optional)

| Var | Default | Purpose | |-----|---------|---------| | PROOF402_URL | https://four02proof.onrender.com | Payment facilitator |

Full server (optional later)

If you want a ready-made tool catalog too:

npx @scriptmasterlabs/mcp-x402
# remote: https://mcp-x402.onrender.com/mcp

Still start here: charge your own tools first.

License

MIT