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Agent Evidence API – Claim Verification
x402
Agent Evidence API – Claim Verification is a paid API for AI agents from agent-evidence-api.thx93.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-29).
Verifies a claim or fact-checks a statement against up to 5 specified public web sources, returning cited evidence passages that support, contradict, or fail to settle the claim.
Price / call$0.01
Success—
StatusUnknown
How this service works
Verify a claim or fact check a statement against public web sources: send a question and up to 5 URLs, get cited evidence - passages that support, contradict or fail to settle it. Claim verification with a citation for every excerpt: source URL, retrieval time, content hash. Never charges when nothing is retrieved. Free to evaluate: the `sample` tool returns one real response at no cost, so you can judge the output before paying for your own question.
Output
Returns an array of evidence result objects, each containing a passage of text from the retrieved web source, a verdict of whether it supports, contradicts, or fails to settle the claim, the source URL, the retrieval timestamp, and a content hash for auditability. If nothing is retrieved, no charge is applied.
Example use cases
Fact-checking a health claim
“I've seen people saying that 'vitamin C cures the common cold' — can you verify that claim against these three sources and give me the exact excerpts that support or contradict it, with their source URLs and retrieval times? https://www.mayoclinic.org/drugs-supplements-vitamin-c/art-20363932, https://www.nih.gov/news-events/nih-research-matters/vitamin-c-does-not-prevent-colds, https://www.cochrane.org/CD000980/ARI_vitamin-c-for-preventing-and-treating-the-common-cold”
Legal or regulatory statement verification
“Please verify whether 'GDPR requires companies to respond to data access requests within 30 days' is accurate by checking these two pages and returning the specific cited passages: https://gdpr-info.eu/art-12-gdpr/ and https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/individual-rights/right-of-access/”
Checking a product specification claim
“Can you fact-check the statement 'The Tesla Model 3 Long Range has a 358-mile EPA range' against these URLs and tell me whether the passages support, contradict, or are inconclusive about it — with the exact text, source URL, and content hash for each: https://www.tesla.com/model3 and https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=48218”
Technical details
Endpoint
POSThttps://agent-evidence-api.thx93.workers.dev/weather/mcp?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need grounded, cited evidence for or against a specific claim, particularly when you have specific authoritative URLs to check against. It is superior to general web search when auditability matters — each result includes a source URL, retrieval time, and content hash. Prefer it over LLM-generated fact-checks when you need verifiable, non-hallucinated source passages. It is especially valuable in journalism, compliance, legal research, and scientific contexts where traceable citations are required.
Side effects
- Source URL is inaccessible or returns a non-200 response — no evidence retrieved, no charge
- Claim is too ambiguous for any passage to be matched — returns inconclusive results
- URL content is behind a paywall or requires authentication — retrieval fails silently
- More than 5 URLs supplied — schema validation error
- MCP tool name or input schema missing — request rejected with schema error
- Rate limits or network errors from Cloudflare Workers — transient 5xx response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"result": [
{
"area": "Central Virginia",
"event": "Winter Storm Warning",
"severity": "Severe",
"description": "Heavy snow expected.",
"instructions": "Avoid travel."
}
]
}
}Tags
x402
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