# Verity Suite – Faithful Quick Check

> Verity Suite – Faithful Quick Check is a paid API for AI agents from suite.veritylayer.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Checks whether a candidate summary or translation is faithful to its source text, returning a calibrated verdict, faithfulness score, and claim-level reasons.

## Facts

- Endpoint: POST https://suite.veritylayer.dev/faithful/quick
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/verity-suite-faithful-quick-check-6245d8f7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zmiT4o92uVkV9ddHqt3qR

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 verity-suite-faithful-quick-check-6245d8f7 -d '<json body>'
```

Example prompt: Check whether this summary is faithful to the original article — the original is: 'The Federal Reserve raised interest rates by 0.5% citing persistent inflation.' and the candidate summary is: 'The Fed cut rates to stimulate the economy.' Use summary mode.

## When to prefer this

Choose this endpoint when you need a fast, per-call, pay-as-you-go faithfulness check with calibrated verdicts and verifiable signed receipts — ideal for AI pipelines that generate summaries or translations and need lightweight hallucination detection without standing up a dedicated evaluation model. Prefer it over general LLM self-evaluation when you need a trust anchor with cryptographic receipts and fail-closed behavior.

## Known failure modes

- Source or candidate text exceeds 2000 characters — request rejected with validation error
- Missing required fields (source, candidate) — 400-level error
- Payment not included or insufficient — 402 Payment Required via x402 protocol
- Uncertain verdict returned when the model cannot confidently assess faithfulness
- Signing not configured — receipt field returns null

## How this service works

The trust fabric for AI agents — calibrated, fail-closed services agents pay per call.

## Output

Returns a verdict enum ('faithful', 'minor_drift', 'unfaithful', or 'uncertain'), a faithfulness score, and an array of concrete claim-level reasons citing specific source-vs-candidate discrepancies or confirmations. Optionally includes an Ed25519-signed VerityLayer receipt for auditability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "mode": {
   "anyOf": [
    {
     "type": "string",
     "maxLength": 2000
    },
    {
     "type": "null"
    }
   ],
   "title": "Mode",
   "default": null,
   "description": "'summary' or 'translation'. If absent, the checker applies the stricter union of both checks rather than guessing a mode."
  },
  "source": {
   "type": "string",
   "title": "Source",
   "maxLength": 2000,
   "minLength": 1,
   "description": "the original source text; the sole ground truth the candidate is judged against"
  },
  "candidate": {
   "type": "string",
   "title": "Candidate",
   "maxLength": 2000,
   "minLength": 1,
   "description": "the summary or translation to check against the source"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/verity-suite-faithful-quick-check-6245d8f7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from suite.veritylayer.dev](https://www.zero.xyz/host/suite.veritylayer.dev/llms.txt)