Hallucination Detection Prompt
Catch the confident invention — check an AI output's claims against its source and flag every statement that isn't supported, with the unsupported span quoted.
Overview
The dangerous AI failure isn't being wrong loudly — it's being wrong confidently, with an invented fact that reads exactly like a real one. This prompt audits an output against its source material: it extracts the checkable claims, marks each as supported, contradicted, or unsupported, and quotes the exact span that isn't backed by the source — so hallucinations are caught before a user trusts them.
Why This Works
- Classifying every claim catches the plausible invention, not just obvious errors
- Quoting the unsupported span makes the finding actionable, not vague
- Judging only against the source is what separates hallucination from 'sounds right'
Best for
- RAG systems and summarizers grounded in source text
- High-stakes outputs where a wrong fact is costly
- Evaluation pipelines needing a hallucination check
Not for
- Open-ended generation with no source to check against
- Grounded-answer verification specifically — use the Groundedness Check Prompt
Use cases
- Checking a RAG or summary output against its source
- Catching invented facts before they reach a user
- Auditing agent answers for unsupported claims