GPT-5.5 x402 API Gateway

Generate a deterministic buyer integration package for an x402/MCP service: MCP remote server config, Claude Desktop-style config hints, curl discovery checks, x402 quote test commands, endpoint selection, spending caps, and verification checklist without calling an upstream model. GET variant for agents, crawlers, and wallets that prefer query parameters over a JSON body. Pay up to $0.006 per request with x402 USDC on Base.

Call it in 30 seconds

// npm i x402-fetch viem
import { wrapFetchWithPayment } from "x402-fetch";
import { createWalletClient, http } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { base } from "viem/chains";

const account = privateKeyToAccount(process.env.PRIVATE_KEY); // funds USDC on Base
const wallet = createWalletClient({ account, chain: base, transport: http() });
const fetchWithPay = wrapFetchWithPayment(fetch, wallet);

// Pays the $0.006 USDC automatically on the 402, then returns the real response:
const res = await fetchWithPay("https://gpt55.558686.xyz/v1/tools/x402-mcp-integration-kit", { method: "GET" });
console.log(await res.json());

# pip install x402 eth-account httpx
import os, asyncio
from eth_account import Account
from x402.clients.httpx import x402HttpxClient

account = Account.from_key(os.environ["PRIVATE_KEY"])  # funds USDC on Base

async def main():
    async with x402HttpxClient(account=account) as client:
        # x402 handles the 402 -> pay ($0.006 USDC) -> retry automatically
        r = await client.get("https://gpt55.558686.xyz/v1/tools/x402-mcp-integration-kit")
        print((await r.aread()).decode())

asyncio.run(main())

# 1) An unpaid request returns HTTP 402 with the exact payment terms:
curl -i "https://gpt55.558686.xyz/v1/tools/x402-mcp-integration-kit?base_url=https://gpt55.558686.xyz&max_usdc_per_call=0.01&service_name=GPT-5.5 x402 Gateway"

# 2) Paying + retrying requires an x402 client that can sign the USDC
#    authorization (curl alone cannot). See the JS / Python tabs below.

New to x402? Read the 5-minute quickstart →