Missing-context hallucinations (Anthropic)
Only in system cards
Models get prompts that request tools they lack or cite missing material. Score is the non-hallucination rate on each 500-prompt set.
In-house Anthropic evaluation with unavailable-tool and missing-reference sets. The tool set was filtered on Claude Opus 4.6 failures.
Made by Anthropic Hallucination rates Tasks kept private Last in a system card May 2026
Last model added May 2026
- Level
- Everyday Most adults, without training
- Scored
- Graded by a model A language model scores each response, usually against a rubric.
- Answers
- Open-ended Free-form text, documents, designs or media judged as a whole.
1
System card reports it, from 1 lab
No scores here yet
No lab, leaderboard or Epoch AI run has reported a score for Missing-context hallucinations (Anthropic) yet.
Labs report it only in system cards
We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark. Some system cards do, below.
One system card reports it
Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| 28 May 2026 | Claude Opus 4.8 system card | Missing-context hallucinations, non-hallucination rate, no overall: unavailable tools 95%, missing references 91%, printed on chart (6.3.3.4, Figure 6.3.3.4.A) | Hallucination |
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