SKILL.md Raw

x402 client

Safety rules

Only pay when the user has explicitly allowed it and set a budget: a maximum per request and a maximum total for the session. Default to asking before every payment if no budget is given.
Read the wallet key from an environment variable (AGENT_PRIVATE_KEY). Never print it, log it, or ask the user to paste it into the conversation. Recommend a dedicated low-balance wallet.
Before paying, show the user: resource URL, amount in USD, network and payTo.

Inspect a 402

curl -s -i https://api.example.com/paid-endpoint

The JSON body's accepts lists acceptable payments. Pick the entry whose network your wallet is funded on. maxAmountRequired is in the token's smallest unit (USDC: 6 decimals, so 10000 = $0.01). Refuse if it exceeds the per-request budget.

Pay with x402-fetch (Node)

npm install x402-fetch viem

import { wrapFetchWithPayment, decodeXPaymentResponse } from "x402-fetch";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.AGENT_PRIVATE_KEY);
// third argument: maximum payment in base units (here $0.10)
const pay = wrapFetchWithPayment(fetch, account, BigInt(100_000));

const res = await pay("https://api.example.com/paid-endpoint");
console.log(res.status, await res.json());
const receipt = res.headers.get("x-payment-response");
if (receipt) console.log(decodeXPaymentResponse(receipt)); // { success, transaction, network, payer }

Python

pip install x402 eth-account httpx

import os
from eth_account import Account
from x402.clients.httpx import x402HttpxClient

account = Account.from_key(os.environ["AGENT_PRIVATE_KEY"])
async with x402HttpxClient(account=account, base_url="https://api.example.com") as client:
    r = await client.get("/paid-endpoint")
    print(r.status_code, r.json())

After paying