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Verity Suite – Faithful (Faithfulness Checker)
x402
Verity Suite – Faithful (Faithfulness Checker) is a paid API for AI agents from suite.veritylayer.dev, paid per call via x402, $0.15/call, status unknown (last checked 2026-09-14).
Checks whether a candidate summary or translation faithfully represents its source text, returning a calibrated verdict and claim-level reasons.
Price / call$0.15
Success—
StatusUnknown
How this service works
The trust fabric for AI agents — calibrated, fail-closed services agents pay per call.
Output
Returns a verdict ('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 independent verification.
Example use cases
AI summarizer hallucination audit
“My AI just summarized this research paper paragraph — source: 'The drug reduced tumor size by 23% in 78% of patients over 12 weeks with no serious adverse events.' Candidate: 'The drug eliminated tumors in most patients with no side effects.' Can you check if that summary is faithful or if it exaggerates the claims?”
Legal document translation check
“I need to verify that this French-to-English translation of a contract clause is accurate — source: 'Le preneur s'engage à payer le loyer avant le premier jour de chaque mois.' Candidate: 'The tenant agrees to pay rent by the first day of each month.' Run a faithfulness check in translation mode.”
News article summary validation
“Before we publish this AI-written summary, check it for faithfulness against the original — source: 'City council approved a $4.2 million budget increase for road repairs, with three council members dissenting.' Candidate: 'The city council approved additional road repair funding.' Mode: summary — tell me if anything material was dropped or distorted.”
Technical details
Endpoint
POSThttps://suite.veritylayer.dev/faithful/proWhen to prefer
Choose this endpoint when you need a calibrated, auditable faithfulness verdict for AI-generated summaries or translations, especially in pipelines where hallucination or factual drift must be caught before content is published, acted upon, or passed downstream. The signed receipt feature makes it suitable for compliance-sensitive workflows where proof of verification is needed. Prefer it over generic LLM self-evaluation when you need structured verdicts with claim-level reasoning rather than free-form critique.
Side effects
- Source or candidate text exceeds 2000 character limit — request rejected with validation error
- Missing required fields (source, candidate) — returns schema validation error
- Ambiguous mode when both summary and translation interpretations conflict — applies stricter union check which may yield 'uncertain' verdict
- Network or service unavailability — fail-closed behavior means no permissive fallback is returned
- Invalid bodyType or method — request rejected at schema validation
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| mode | — | 'summary' or 'translation'. If absent, the checker applies the stricter union of both checks rather than guessing a mode. |
| source | string | the original source text; the sole ground truth the candidate is judged against |
| candidate | string | the summary or translation to check against the source |
Tags
x402
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