# Agent Evidence API

> Agent Evidence API is a paid API for AI agents from agent-evidence-api.thx93.workers.dev, paid per call via x402, $0.003/call, status down (last checked 2026-10-16).

Verifies a claim against up to 5 public web URLs, returning cited passages that support, contradict, or fail to settle the claim, each with a source URL, retrieval timestamp, and content hash.

## Facts

- Endpoint: POST https://agent-evidence-api.thx93.workers.dev/v1/evidence?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: down
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-evidence-api-57b703bd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qoKjg3hLfJENY-f9tloaC

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-57b703bd -d '<json body>'
```

Example prompt: Can you check whether the claim 'the Eiffel Tower is 330 meters tall' is supported or contradicted by these two sources: https://en.wikipedia.org/wiki/Eiffel_Tower and https://www.toureiffel.paris/en — and give me the exact cited passages with timestamps?

## When to prefer this

Choose this endpoint when you need traceable, cited evidence for or against a specific claim, grounded in particular URLs the user or agent specifies. It is ideal when auditability matters (content hash, retrieval time) and when you want verdict-tagged passages rather than a generic web search summary. Prefer it over general search APIs when you already have candidate sources and need structured evidence extraction with citation metadata.

## Known failure modes

- URL is inaccessible, paywalled, or returns no retrievable content — passage not returned, no charge
- Claim is too ambiguous for clear support/contradiction classification — returned as inconclusive
- More than 5 URLs submitted — request rejected or truncated
- Source content has changed since retrieval — hash reflects retrieval-time snapshot only
- Network timeout or worker error — HTTP 5xx returned

## How this service works

Verify a claim 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.

## Output

Returns cited evidence excerpts from the provided URLs, each labeled as supporting, contradicting, or inconclusive relative to the claim, along with the source URL, retrieval timestamp, and a content hash for auditability. If no content is retrieved, no charge is incurred.

## 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"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-evidence-api-57b703bd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-evidence-api.thx93.workers.dev](https://www.zero.xyz/host/agent-evidence-api.thx93.workers.dev/llms.txt)