# FactStamp Dated Claim Verifier

> FactStamp Dated Claim Verifier is a paid API for AI agents from factstamp.agentrails.workers.dev, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-16).

Checks a specific dated numeric or factual claim against Australian primary-source data series and returns a verdict of verified, stale, contradicted, or unknown with an as-of date.

## Facts

- Endpoint: POST https://factstamp.agentrails.workers.dev/check?utm_source=zero.xyz
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/factstamp-dated-claim-verifier-7ad7db0a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_J3-KVw_pe5bS_j3htOJ7W

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 factstamp-dated-claim-verifier-7ad7db0a -d '<json body>'
```

Example prompt: Before I put this in the slide deck, can you check whether 'The RBA cash rate is 4.35% as at August 2026' is still accurate according to the Reserve Bank of Australia's own published series?

## When to prefer this

Choose this endpoint when you need to verify a specific dated numeric or statistical claim against Australian government or authoritative primary-source series — particularly for economic indicators, central bank rates, or ABS statistics — before committing that figure to a document, model, or decision. It is purpose-built for single-claim validation with a clear verdict signal rather than general web search or broad fact-checking.

## Known failure modes

- Claim outside Australian primary-source coverage returns verdict 'unknown' rather than an error
- Unrecognised or ambiguous series returns unknown verdict
- Malformed request body returns HTTP 400
- Payment not processed or insufficient USDC balance returns HTTP 402
- Service unavailable returns HTTP 503

## How this service works

Check a dated figure you are about to act on against the publisher's own series, and receive verified, stale, contradicted or unknown with the as-of date. Call it before committing a number to a page, deck, model or decision. Coverage today is Australian primary sources; anything outside coverage returns unknown rather than a guess.

## Output

A JSON object containing the verdict (one of: verified, stale, contradicted, or unknown), the as-of date for the data, the publisher name, the matched series ID, and the original claim string submitted. Returns 'unknown' rather than guessing when the claim falls outside current Australian primary-source coverage.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "as_of": "2026-08-01",
  "claim": "The RBA cash rate is 4.35% as at August 2026",
  "verdict": "contradicted",
  "publisher": "Reserve Bank of Australia",
  "series_id": "rate.rba_cash_target"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/factstamp-dated-claim-verifier-7ad7db0a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from factstamp.agentrails.workers.dev](https://www.zero.xyz/host/factstamp.agentrails.workers.dev/llms.txt)