{"uid":"cap_wR-OKgmReoW7Hdbwue8tq","slug":"fact-check-claim-against-sources-44cf9447","name":"Fact-Check Claim Against Sources","description":"Fact-check a claim against one to three supplied sources","url":"https://red-breeze-8b8c.keenanbooker83.workers.dev/fact-check","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"claim":{"type":"string","maxLength":4000,"minLength":1,"description":"Factual claim to check."},"sourceUrls":{"type":"array","items":{"type":"string","maxLength":2048,"minLength":1},"maxItems":3,"minItems":1,"description":"One to three public source URLs against which the claim is checked."}}},"responseSchema":{"type":"json","example":{"agent":"Fact-Checking Agent","verdict":"supported","confidence":0.99,"explanation":"The supplied official sources state that Congress approved the declaration on December 8, 1941.","requestAccepted":true}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.04","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":"$0.04/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.04","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.04","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_HZ3ydKaGuEoSXh3ca_Dw-","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.04","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Checks a factual claim against one to three supplied source URLs and returns a verdict on its accuracy","exampleAgentPrompt":"Can you fact-check this claim — 'Global average temperatures have risen by 1.1°C since pre-industrial times' — against these two sources: https://www.nasa.gov/climate and https://www.ipcc.ch/report/ar6/wg1/?","exampleUseCases":[{"title":"Verify journalist's claim before publishing","prompt":"Before we publish this article, fact-check the claim 'The US spends more per capita on healthcare than any other developed nation' against these sources: https://www.commonwealthfund.org/publications/issue-briefs/2023/jan/us-health-care-global-perspective-2022 and https://data.oecd.org/healthres/health-spending.htm"},{"title":"Debunk viral social media post","prompt":"Someone shared a post claiming 'Eating chocolate daily reduces heart disease risk by 30%' — can you check that claim against this source: https://www.health.harvard.edu/heart-health/chocolate-and-heart-health?"},{"title":"Research assistant verifying student paper","prompt":"I'm reviewing a student essay that says 'The Great Wall of China is visible from space with the naked eye' — please fact-check that claim against these two sources: https://www.nationalgeographic.com/science/article/great-wall-china-visible-space and https://www.smithsonianmag.com/smart-news/great-wall-china-not-visible-space"}],"resultDescription":"Returns a structured fact-check verdict indicating whether the supplied claim is supported, partially supported, contradicted, or unverifiable based on the provided source URLs, along with relevant excerpts or reasoning drawn from those sources.","failureModes":["Source URL is inaccessible, paywalled, or returns a non-200 response — endpoint may return an error or incomplete analysis","Claim is too vague or opinion-based to be fact-checkable — may return an indeterminate verdict","Source URLs do not contain information relevant to the claim — returns a 'not addressed by sources' result","Claim text exceeds 4000 characters — request will be rejected with a validation error","More than three source URLs provided — request will be rejected","Claim is in a language not supported by the underlying model — may produce inaccurate results"],"whenToPreferThis":"Use this endpoint when you have a specific factual claim and one to three concrete source URLs to check it against. It is distinct from a general web search or source credibility evaluator — it performs targeted claim-vs-source verification rather than open-ended research. Prefer this over the sibling 'verify citation' endpoint when you need a broader fact-check that may draw on multiple sources simultaneously rather than verifying a single exact quotation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T00:43:35.793Z","isFirstParty":false}