CharXiv Reasoning (Fable/Mythos No Tools): leaderboard
CharXiv Reasoning results as reported in the Claude Fable 5 / Mythos 5 system card, No Tools configuration — Anthropic-run evaluation comparing a small set of frontier models.
Metric: Score (%). Source: www-cdn.anthropic.com. Saturation forecast: Around January 2027. 3 models tracked.
Top models
| # | Model | Score | Overall rank |
|---|---|---|---|
| 1 | Claude Mythos 5 | 88.9 | #2 |
| 2 | Claude Mythos Preview | 86.2 | #4 |
| 3 | Claude Opus 4.8 | 80.5 | #37 |
No result here: #3 Claude Opus 5.5, #6 GPT-6 Astra, #7 GPT-6.1 Sol.
Interactive version: theaggregate.ai/benchmark?slug=charxiv-reasoning-fable-mythos-no-tools · How It Works · Data refreshed daily, snapshot 2026-10-20.