Anthropic
Claude Fable 5.1 (Adaptive Reasoning, Medium Effort, Default Fallback)
Claude Fable 5.1 improves on Fable 5 across long-running agentic coding, knowledge work, and research, following instructions precisely over sessions that run unattended for hours.
Claude release notesModel Snapshot
TypeLanguage
ReleaseAug 31, 2026
Context1,000,000
Tagsreasoning, tool-use, explicit-caching, file-input
Overall
Rank #20 across 687
48.9
Coding
Rank #9 across 330
77.1
Blended Price
Rank #415 across 432
$20.00/M
Strength Profile
Percentile score by analysis domain.
* Cost is inverted: lower input, output, and blended prices rank higher.
Benchmark Percentiles
Higher bars mean stronger relative placement.
Model Details
Runtime
Output Speed50.1 tok/s
First Token5.54s
Max Output128,000
Pricing
Blended$20.00/M
Input$10.00/M
All Benchmarks
| Metric | Domain | Value | Rank |
|---|---|---|---|
| Artificial Analysis Intelligence Index | overall | 48.9 | #20 |
| Artificial Analysis Coding Index | coding | 77.1 | #9 |
| GPQA | reasoning | 88.6% | #91 |
| Humanity's Last Exam | reasoning | 53.8% | #13 |
| SciCode |