Web answer

AI-generated answer to a natural-language question, grounded in live web search results with source citations. Returns clean prose plus a structured citations array (URL, snippet, favicon) — backed by an independent search index, not the model's training data. Useful when an agent needs a synthesized answer plus the receipts to verify or follow up.

Input

Field	Type	Description
q *	string	Natural-language question (max 400 chars)
country	string	Optional 2-letter country code (default us)
language	string	Optional 2-letter language code (default en)
max_tokens	integer	Optional cap on the generated answer length in tokens (default 1024, min 64, max 4096). Lower for TL;DR; higher for research questions.

Example output

{
  "query": "what is the x402 payment protocol?",
  "answer": "x402 is an open standard for internet-native, pay-per-request HTTP APIs that uses the HTTP 402 \"Payment Required\" status code to negotiate and settle micro-payments inline with the original request.",
  "citations": [
    {
      "url": "https://www.x402.org/",
      "snippet": "x402: An open standard for internet-native payments.",
      "favicon": "https://imgs.search.brave.com/...",
      "number": 1
    }
  ],
  "citationCount": 1
}

Try it — see the 402 challenge (free)

curl -i "https://agent402.tools/api/answer?q=what+is+the+x402+payment+protocol%3F"

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

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();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/answer?q=what+is+the+x402+payment+protocol%3F");

Wallet-only. This tool reaches the network/browser/storage, so it is paid in USDC via x402 (no proof-of-work tier).

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