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AIAlign Hallucination Rate - Lexical Coverage Screener
x402
AIAlign Hallucination Rate - Lexical Coverage Screener is a paid API for AI agents from aialign.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-16).
Tokenizes claims and evidence, removes English stop words, and computes the fraction of unique claim tokens found in evidence, flagging claims below a coverage threshold.
Price / call$0.004
Success—
StatusUnknown
How this service works
Tokenizes each claim and its supplied evidence, removes a small declared English stop-word list, and reports the fraction of unique claim tokens present in evidence. Coverage below a supplied threshold is flagged. This is lexical grounding screening only: overlap does not prove truth, low overlap does not prove hallucination, and the service does not retrieve or validate evidence.
Output
Returns per-claim results including the computed coverage fraction (ratio of unique claim tokens found in evidence), a flag indicating whether coverage fell below the supplied minimum_coverage_fraction threshold, and the original claim_id for cross-referencing.
Example use cases
RAG pipeline output auditing
“I have a batch of 50 answers my RAG system generated — each one has its retrieved context. Can you check what fraction of each answer's key terms actually appear in the retrieved passages, and flag anything below 50% coverage so I know which answers might be hallucinated?”
LLM fact-check before publication
“Before I publish this AI-written article, run a lexical grounding check on each factual claim against the source documents I provided — use a 70% minimum coverage threshold and tell me which claims are flagged.”
Automated eval in CI pipeline
“As part of my model evaluation run, check these 200 model-generated claims against their reference evidence texts and give me the coverage fraction for each one — I want to catch any that fall below 0.4 so I can review them manually.”
Technical details
Endpoint
POSThttps://aialign.halowerk.com/v1/hallucination-rateWhen to prefer
Choose this endpoint when you need a fast, cheap, deterministic lexical screening of LLM output grounding — especially in batch eval pipelines, CI/CD model testing, or RAG output auditing where you want a first-pass signal on which claims lack evidence token overlap. It is not a semantic entailment checker or a truth verifier; prefer it over heavier NLI/embedding-based approaches when speed and cost matter and you understand its lexical-only limitations.
Side effects
- Empty claims array returns validation error
- claim_text or evidence_texts exceeding character limits rejected
- minimum_coverage_fraction outside [0,1] range causes validation error
- Very short claims may produce unreliable coverage fractions due to small token counts
- Non-English text may behave unpredictably since stop-word list is English-only
- Payment failure via x402 protocol returns 402 before processing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claims | array | |
| minimum_coverage_fraction | number |
Tags
x402
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