Toolathlon (Anthropic Internal Harness): leaderboard
Anthropic internal Toolathlon harness over 108 tool-use tasks, reporting pass@1 for agentic workflow completion.
Metric: Pass@1 (%). Source: www-cdn.anthropic.com. Saturation forecast: Around February 2028. 7 models tracked.
Top models
| # | Model | Score | Overall rank |
|---|---|---|---|
| 1 | Claude Fable 5 | 61.7 | #16 |
| 2 | Claude Mythos 5 | 61.7 | #2 |
| 3 | Claude Mythos Preview | 61.1 | #4 |
| 4 | Claude Opus 4.8 | 59.9 | #37 |
| 5 | Claude Opus 4.7 | 59.3 | #49 |
| 6 | Claude Opus 4.6 | 56.8 | #63 |
| 7 | Claude Sonnet 4.5 | 41 | #142 |
No result here: #3 Claude Opus 5.5, #6 GPT-6 Astra, #7 GPT-6.1 Sol.
Interactive version: theaggregate.ai/benchmark?slug=toolathlon-anthropic-internal-harness · How It Works · Data refreshed daily, snapshot 2026-10-20.