# Fact Check / Verify Claim Against Live Web Sources

> Fact Check / Verify Claim Against Live Web Sources is a paid API for AI agents from agent-data-tools.revmesh2074.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-30).

Searches the live web via Brave, reads top pages, and uses Llama 4 Scout to return a verdict (supported, contradicted, mixed, or unverified) with explanation and citations for a given claim.

## Facts

- Endpoint: GET https://agent-data-tools.revmesh2074.workers.dev/ai/fact-check?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Provider: agent-data-tools.revmesh2074.workers.dev
- Website: https://agent-data-tools.revmesh2074.workers.dev
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-data-tools-revmesh2074-workers-dev-fact-check-verify-claim-22ff0e26
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1F28Qi9018PAhktMm6f0y

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agent-data-tools-revmesh2074-workers-dev-fact-check-verify-claim-22ff0e26
```

Example prompt: Before you include this in the report, can you fact-check the claim that 'the Amazon rainforest absorbs 2 billion tons of CO2 per year' against live web sources and tell me if it's supported, contradicted, or mixed?

## When to prefer this

Choose this endpoint when an AI agent needs a fast, automated pre-flight check on a specific claim before repeating or acting on it — especially in pipelines that generate or relay factual statements. Prefer this over manual search when you want a structured verdict with citations in a single call. Not a substitute for authoritative editorial fact-checking; best suited for screening, not definitive adjudication. Use when the claim is self-contained and under 400 characters.

## Known failure modes

- Claim exceeds 400 characters — request rejected
- Brave search returns no relevant results — verdict returned as 'unverified'
- Top pages are paywalled or dynamically rendered and cannot be read — limited source quality
- Model may misinterpret ambiguous or context-dependent claims
- Results reflect model reading of search snippets, not authoritative editorial fact-checking
- Transient Brave API or Workers AI outage — HTTP 5xx returned

## How this service works

Check a claim against the live web in one call: a Brave search, the top pages read, and a verdict from Llama 4 Scout using those sources only (supported, contradicted, mixed or unverified) with a short explanation, [n] citations and the sources. A model's reading of a few search results, not an editorial fact-check. Results are for immediate use only (Brave API terms). Use to screen a statement before an agent repeats or acts on it.

## Output

Returns a JSON object containing: the original claim, the model used (Llama 4 Scout), a terms field, a verdict string (supported, contradicted, mixed, or unverified), a short natural-language explanation of the verdict, and an array of numbered source citations each with URL and title. Results are for immediate use only per Brave API terms.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "claim"
 ],
 "properties": {
  "claim": {
   "type": "string",
   "description": "The claim to check, at most 400 characters"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string"
  },
  "model": {
   "type": "string"
  },
  "terms": {
   "type": "string"
  },
  "sources": {
   "type": "array",
   "items": {
    "type": "object",
    "properties": {
     "n": {
      "type": "number"
     },
     "url": {
      "type": "string"
     },
     "title": {
      "type": "string"
     }
    }
   }
  },
  "verdict": {
   "type": "string"
  },
  "explanation": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-data-tools-revmesh2074-workers-dev-fact-check-verify-claim-22ff0e26/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-data-tools.revmesh2074.workers.dev](https://www.zero.xyz/host/agent-data-tools.revmesh2074.workers.dev/llms.txt)