Core limitations
- Public or authorized sources can be wrong, stale, inaccessible, manipulated, duplicated or incomplete.
- Claim extraction can miss material content or split it incorrectly; coverage is an estimator, not proof of completeness.
- Entailment and contradiction judgements are model-assisted and can be mistaken.
- Search availability and provider behavior can change between otherwise identical runs.
- Dynamic facts require an explicit as-of time; legal and policy facts require jurisdiction and effective date.
- Correlated publications can look independent when they ultimately repeat one underlying source.
High-stakes use
Medical, legal, financial, safety, employment, insurance, eligibility, and other consequential decisions require a qualified human and the authoritative source itself. The corresponding profiles raise evidence and review expectations; they do not create professional advice.
Unverifiable is a useful result
Absence of suitable evidence is not evidence that a claim is true or false. Mephistopheles keeps this state explicit so downstream systems can escalate, defer, request more context, or block publication.
Adversarial content
Submitted text and retrieved pages are treated as untrusted evidence, not instructions. Prompt-isolation controls reduce injection risk, but no prompt-based boundary is absolute. Secrets and unnecessary sensitive content should never be submitted.
Availability
The service depends on network, database, retrieval and model providers. Partial provider outages may produce an explicit failure or more abstention; they must not be silently converted into a clean result.