{"uid":"cap_0IKKAIX7RSr0KQqSDiTUx","slug":"x402-agent-services-web-answer-ai-powered-q-a-b4f7322c","name":"x402 Agent Services – Web Answer (AI-powered Q&A)","description":"USDC pay-per-call APIs for AI agents via the x402 protocol (v2, exact, Base mainnet). Send a request, receive HTTP 402 with payment requirements, pay with @x402/fetch or any x402 client, retry with the PAYMENT-SIGNATURE header.","url":"https://call402.com/api/web-answer?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"query":{"type":"string","description":"Natural-language question"}}},"responseSchema":{"type":"json","example":{"meta":{"source":"exa-answer","request_id":null,"citations_count":1},"query":"What is the current price of ETH?","answer":"ETH is trading at about $4,100.","citations":[{"url":"https://example.com","title":"Example source","author":null,"published_date":"2026-10-01"}]}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_tue7Db3NSXDyRdeBF5_2r","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Answers a natural-language question with a cited AI-generated response, sourced from live web content via Exa, billed at $0.02 USDC per call via the x402 micropayment protocol on Base mainnet.","exampleAgentPrompt":"What is the current market cap of Bitcoin, and where does that information come from?","exampleUseCases":[{"title":"Real-time crypto price lookup","prompt":"What is the current price of ETH and where is that data coming from?"},{"title":"Breaking news fact check","prompt":"What happened with the SEC and Ethereum ETFs this week? Give me a short answer with sources."},{"title":"Live regulatory research","prompt":"What are the current capital gains tax rates for crypto in the US? I need a sourced answer."}],"resultDescription":"Returns a JSON object containing an AI-generated answer string, the original query, citation count, and an array of citations each with URL, title, optional author, and published date. The meta object includes the source identifier ('exa-answer') and a request_id.","failureModes":["HTTP 402 returned before payment — agent must pay with PAYMENT-SIGNATURE header and retry","Insufficient USDC balance on Base mainnet causes payment failure","Malformed or missing 'query' field returns a 400-level error","Query yields no matching web sources, resulting in an empty or low-confidence answer","Network timeout if the Exa backend is slow to respond","Invalid x402 client version incompatible with v2/exact payment scheme"],"whenToPreferThis":"Choose this endpoint when you need a cited, real-time answer to a factual or current-events question and you are operating in an x402-capable agent environment with a USDC wallet on Base mainnet. It is especially useful when freshness matters (prices, news, regulations) and you need traceable sources rather than a hallucinated answer. Prefer alternatives if you need bulk queries, streaming responses, or cannot execute micropayments programmatically.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-19T12:37:39.475Z","isFirstParty":false,"canonicalSlug":"x402-agent-services-web-answer-ai-powered-q-a-b4f7322c"}