# Crucible Fact-Check

> Crucible Fact-Check is a paid API for AI agents from crucible.unitynodes.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Verifies a text claim against online sources and returns a verdict with citations, evidence, confidence score, and risk score.

## Facts

- Endpoint: POST https://crucible.unitynodes.com/research/fact-check
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/crucible-fact-check-f9d8a64a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bBVrHKuI0qL6AM-y-OiS5

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 crucible-fact-check-f9d8a64a -d '<json body>'
```

Example prompt: Can you fact-check this claim for me: 'Ethereum completed its Merge transition to proof-of-stake in September 2022' — I need a verdict, cited sources, and a confidence score.

## When to prefer this

Choose this endpoint when you need a cited, evidence-backed verdict on a specific factual claim — especially for Web3, crypto, or blockchain topics — and require auditability via a content hash. Prefer it over general search when you need structured evidence objects and confidence scoring rather than raw search results.

## Known failure modes

- Claim is too vague or ambiguous to verify — low confidence score returned
- No reliable sources found for the claim — verdict may be 'unverified'
- External web sources unavailable or rate-limited — incomplete citations
- Claim contains highly niche or very recent information not yet indexed — low evidence coverage
- Payment not processed (x402 flow failure) — 402 response returned before result

## How this service works

Pay-per-call Web3 agent services: wallet, token and agent security audits; token prices, depeg checks and portfolio valuation; cited fact-checking and source research.

## Output

Returns a verdict string (e.g. true/false/unverified) for the submitted claim, an array of citation objects (URL + title), an evidence array showing which parts of the claim are supported and by which source, a numeric confidence score (0–1), a risk score, a content hash for auditability, and the cost of the call.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "claim"
 ],
 "properties": {
  "claim": {
   "type": "string",
   "description": "Claim to fact-check"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "cost": {
   "type": "number"
  },
  "data": {
   "type": "object",
   "properties": {
    "claim": {
     "type": "string"
    },
    "verdict": {
     "type": "string"
    },
    "citations": {
     "type": "array",
     "items": {
      "type": "object",
      "properties": {
       "url": {
        "type": "string"
       },
       "title": {
        "type": "string"
       }
      }
     }
    }
   }
  },
  "sources": {
   "type": "array",
   "items": {
    "type": "object",
    "properties": {
     "url": {
      "type": "string"
     },
     "hash": {
      "type": "string"
     },
     "name": {
      "type": "string"
     }
    }
   }
  },
  "evidence": {
   "type": "array",
   "items": {
    "type": "object",
    "properties": {
     "claim": {
      "type": "string"
     },
     "support": {
      "type": "string"
     },
     "sourceIndex": {
      "type": "number"
     }
    }
   }
  },
  "riskScore": {
   "type": "number"
  },
  "confidence": {
   "type": "number"
  },
  "contentHash": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/crucible-fact-check-f9d8a64a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from crucible.unitynodes.com](https://www.zero.xyz/host/crucible.unitynodes.com/llms.txt)