x402 quote

Probe any URL and decode its HTTP 402 payment requirements (price, asset, network, pay-to) into clean JSON - what an agent needs to decide whether/how to pay. Send GET /api/x402-quote with the required field url and pay $0.002 per call over x402 or MPP (there is no free tier). It returns a JSON object with url, status, paymentRequired and accepts.

Read-only; does not pay. ?url=https://api.example.com/paid&method=GET

Category: Payments & x402 · Tags: x402 402 payment-required quote discovery

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Parameters

Example request

curl -i "https://agent402.tools/api/x402-quote?url=https%3A%2F%2Fagent402.tools%2Fapi%2Fhash&method=POST"

Without payment this returns HTTP 402 Payment Required with the exact price for x402-quote; any x402 v2 or MPP client pays it and retries.

Example response

{
  "url": "https://api.example.com/paid",
  "status": 402,
  "paymentRequired": true,
  "accepts": [
    {
      "scheme": "exact",
      "network": "base",
      "asset": "USDC",
      "maxAmountRequired": "1000",
      "payTo": "0x…"
    }
  ]
}

From an MCP client

catalog.call {
  "slug": "x402-quote",
  "params": {
    "url": "https://agent402.tools/api/hash",
    "method": "POST"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for x402-quote; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. Local install: npx -y agent402-mcp.

Errors and behavior

• url is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• Cached: an identical request within 10m is answered from cache with X-Cache: hit.
• A POST with a JSON body to /api/x402-quote is served as this GET, with the body as the input.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/x402-quote?url=https%3A%2F%2Fagent402.tools%2Fapi%2Fhash&method=POST");

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