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Verity Suite Faithful — Faithfulness Checker
x402
Verity Suite Faithful — Faithfulness Checker is a paid API for AI agents from verity-suite.onrender.com, paid per call via x402, $0.06/call, status unknown (last checked 2026-09-14).
Checks whether a candidate summary or translation faithfully preserves the meaning of a source text, returning a calibrated verdict and claim-level evidence.
Price / call$0.06
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 calibrated faithfulness probability (0–1), and structured arrays listing specific hallucinations (claims in the candidate not supported by the source), omissions (material source claims dropped), and concrete claim-level reasons explaining the assessment. Fails closed — never returns faithful or minor_drift when uncertain.
Example use cases
Example prompt
“Check if this summary is faithful to the source article — mode is 'summary'. Source: 'The company reported $4.2B in revenue for Q3, up 12% year-over-year, driven by cloud services.' Candidate: 'The company posted record Q3 revenue of $5B, mostly from cloud.' Flag any hallucinations or dropped claims and give me a faithfulness score.”
Technical details
Endpoint
POSThttps://verity-suite.onrender.com/faithfulWhen to prefer
Use this endpoint when an AI agent needs to verify that a generated summary or translation has not hallucinated, omitted material claims, or distorted meaning relative to a known source text. Prefer this over generic LLM self-checks because it is calibrated, fail-closed, and returns structured evidence at the claim level rather than a freeform assessment.
Side effects
- Empty, truncated, or gibberish inputs return verdict 'uncertain' with reasons explaining unreadability
- Texts too misaligned in topic or language to meaningfully compare return 'uncertain'
- A single confirmed factual defect drives faithfulness score well below 0.5 even if most content is accurate
- Missing required 'source' or 'candidate' fields return a 400-level error
- If 'mode' is absent, the stricter union of both summary and translation checks is applied, which may increase false-positive unfaithful verdicts
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| mode | string | 'summary' or 'translation'. If absent, the checker applies the stricter union of both checks rather than guessing a mode. |
| sourcerequired | string | the original source text; the sole ground truth the candidate is judged against |
| candidaterequired | string | the summary or translation to check against the source |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| reasonsrequired | array | concrete claim-level reasons, each either citing a specific source-vs-candidate discrepancy or confirming specific support; at least one reason required |
| verdictrequired | string | faithful=every candidate claim is supported by the source and no material source claim is dropped or distorted; minor_drift=only small non-material omissions/nuance loss that change no core claim, entity, quantity, date, or stance; unfaithful=at least one hallucination, contradiction, negation flip, wrong/invented entity-number-date, dropped material claim, or distortion; uncertain=cannot reliably compare (empty/unreadable/truncated/gibberish input or texts too misaligned to map). FAIL CLOSED: never faithful or minor_drift when unsure. |
| omissions | array | material claims present in the source but dropped or weakened in the candidate |
| faithfulnessrequired | number | calibrated probability the candidate fully preserves source meaning with no hallucination, contradiction, or material distortion; 1=certainly faithful, 0=certainly unfaithful. A single confirmed defect drives this well below 0.5. |
| hallucinations | array | claims asserted in the candidate that are not supported by the source (added or invented content) |
Tags
x402
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