RankingHumanity’s Last Exam
Humanity’s Last Exam
- Bucket
- Hard reasoning
- Unit
- percent
- Direction
- Higher is better
- Version
- —
- Display harness
- Claude Fable 5.1 and Claude Mythos 5.1 System Card
- Board
- https://www.anthropic.com/claude-fable-5-1-mythos-5-1-system-card
Compare published benchmark results with category weights →
Models
1–8 of 8 entries
| Model | Score | Harness | Evidence | Source-recorded date |
|---|---|---|---|---|
| Claude Fable 5.1Anthropic | 60.9%Reported settings & sourceFull2500questions; no tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Fable 5Anthropic | 57.8%Reported settings & sourceFull2500questions; no tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Opus 5Anthropic | 56.6%Reported settings & sourceFull2500questions; no tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Fable 5Anthropic | 63.8%Reported settings & sourceFull2500questions; with tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Fable 5.1Anthropic | 65%Reported settings & sourceFull2500questions; with tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Fable is the safeguarded deployed configuration; selected tasks may use disclosed Opus fallback, except evaluations explicitly counting safety blocks as failures. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Opus 5Anthropic | 63.6%Reported settings & sourceFull2500questions; with tools; auto thinking;1Mtotal token cap; no compaction; Opus4.6grader; restricted fetch and contamination review for tools. Claude Fable 5.1 and Claude Mythos 5.1 System Card · Table 8.1.A;8.12.1 · reviewed 2026-09-24 | Claude Fable 5.1 and Claude Mythos 5.1 System Card | lab self-report | 2026-09-24 |
| Claude Opus 5.5Anthropic | 64.4%Reported settings & sourceFull 2,500 questions; no tools; section 8.11.1 sets thinking to auto, a 1M total token cap, no compaction, and an Opus 4.6 grader. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. Table 8.1.A's default note says adaptive max effort unless otherwise noted. Section 8.11.1 states thinking was set to auto for these runs. Comparison limit: Provider-published lab self-report. Shown as a labeled claim and not admitted as a matched board comparison. Claude Opus 5.5 System Card · Table 8.1.A; section 8.11.1 · reviewed 2026-09-22 | Claude Opus 5.5 System Card | lab self-report | 2026-09-22 |
| Claude Opus 5.5Anthropic | 67.7%Reported settings & sourceFull 2,500 questions; web search, web fetch, programmatic tool calling, and code execution; thinking set to auto; 1M total token cap; no compaction; Opus 4.6 grader; HLE source blocklist and contamination review. Provider-published lab self-report from the Claude Opus 5.5 system card (SHA256 7311c9c6bbb16d012f1c12c7418b05949fcf7ae3e30d2c40f22050074b2a7378). Not an independent board. Launch grid shows 67.7% with tools. Comparison limit: Provider-published lab self-report. Shown as a labeled claim and not admitted as a matched board comparison. Claude Opus 5.5 System Card · Table 8.1.A; section 8.11.1 · reviewed 2026-09-22 | Claude Opus 5.5 System Card | lab self-report | 2026-09-22 |