# Agent Evidence API — Claim Verification

> Agent Evidence API — Claim Verification is a paid API for AI agents from agent-evidence.thx93.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Verifies a claim or fact-checks a statement by retrieving cited evidence passages (supporting, contradicting, or inconclusive) from up to 5 provided URLs.

## Facts

- Endpoint: POST https://agent-evidence.thx93.dev/v1/weather/forecast?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-evidence-api-claim-verification-87168171
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G4v6oW1o-JO63Ru-kFZoh

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-evidence-api-claim-verification-87168171 -d '<json body>'
```

Example prompt: Can you fact-check the claim 'Elon Musk founded Tesla' against these two sources — https://en.wikipedia.org/wiki/Tesla,_Inc. and https://techcrunch.com/tesla-founding — and show me the exact passages that support or contradict it?

## When to prefer this

Choose this endpoint when you need verifiable, cited evidence for a specific claim drawn from a defined set of source URLs — ideal for fact-checking workflows, due diligence, content moderation, or research validation where provenance (source URL, retrieval time, content hash) matters. Prefer it over general web search when you need traceable excerpts rather than ranked links, and when you already have candidate source URLs to check against.

## Known failure modes

- No content retrieved from provided URLs — no charge applied, empty evidence set returned
- URL unreachable or blocked — passage omitted for that source
- Claim is ambiguous — passages may be labeled inconclusive
- Fewer than expected URLs processed if some return errors
- Rate limiting or timeout on external URL fetch

## 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 a set of evidence passages from the provided URLs, each labeled as supporting, contradicting, or failing to settle the claim, along with the source URL, retrieval timestamp, and content hash for auditability. No charge is incurred if no relevant content is retrieved.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "periods": [
   {
    "name": "Today",
    "windSpeed": "5 to 10 mph",
    "temperature": 68,
    "windDirection": "W",
    "temperatureUnit": "F",
    "detailedForecast": "Sunny."
   }
  ],
  "latitude": 37.7749,
  "longitude": -122.4194
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-evidence-api-claim-verification-87168171/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-evidence.thx93.dev](https://www.zero.xyz/host/agent-evidence.thx93.dev/llms.txt)