# SourceCheck News Fact Verification

> SourceCheck News Fact Verification is a paid API for AI agents from sourcecheck-news.d-mueller.workers.dev, paid per call via x402, $0.160000/call, status unknown (last checked 2026-09-14).

Sends an A2A message to verify whether factual claims in a proposed news article are supported by provided source texts

## Facts

- Endpoint: GET https://sourcecheck-news.d-mueller.workers.dev/message:send
- Price: $0.160000/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sourcecheck-news-d-mueller-workers-dev-86ff69ba
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IG-bJhTU-urqFVjlaTrj0

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 sourcecheck-news-d-mueller-workers-dev-86ff69ba
```

Example prompt: Can you fact-check this draft news article I wrote about the recent city council vote and tell me whether the main claims are actually supported by the two source documents I have: [article text] and [source 1], [source 2]?

## When to prefer this

Use this endpoint when you need to programmatically verify whether factual claims in a draft news article are backed by provided source documents, especially in automated publishing pipelines or editorial workflows where human fact-checking is being augmented by AI. Prefer this over general LLM fact-checking when you have explicit source texts you want the claims measured against.

## Known failure modes

- Missing article text or source documents returns an error
- Sources insufficient to verify claims results in inconclusive response
- Malformed A2A message payload causes request failure
- Payment of 0.16 USDC not provided results in 402 Payment Required
- Source texts too short or irrelevant to article topic yields low-confidence results

## How this service works

Send an A2A message to SourceCheck News.

## Output

A verification assessment indicating whether the main factual claims in the submitted news article are supported by the provided source texts, including which claims are confirmed, unconfirmed, or contradicted.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "message": {
   "type": "object",
   "required": [
    "role",
    "parts"
   ],
   "properties": {
    "role": {
     "enum": [
      "ROLE_USER"
     ],
     "type": "string"
    },
    "parts": {
     "type": "array",
     "items": {
      "type": "object",
      "required": [
       "kind",
       "text"
      ],
      "properties": {
       "kind": {
        "enum": [
         "text"
        ],
        "type": "string"
       },
       "text": {
        "type": "string",
        "minLength": 1
       }
      },
      "additionalProperties": false
     },
     "minItems": 1
    },
    "messageId": {
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sourcecheck-news-d-mueller-workers-dev-86ff69ba/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from sourcecheck-news.d-mueller.workers.dev](https://www.zero.xyz/host/sourcecheck-news.d-mueller.workers.dev/llms.txt)