Claude Fable 5.1
Full-repository software refactoring, agentic tool workflows, formal verification, and 1.5M-token needle retrieval.
SWE-bench Verified
82.8%
MMLU-Pro
92.4%
MATH-500
97.9%
Context Window
1,500,000 tokens
| Specification | Value |
|---|---|
| Developer / Lab | Anthropic |
| Parameters Total | Proprietary Frontier |
| Parameters Active | Dynamic Recurrent MoE |
| Architecture Type | Recursive Constitutional Transformer + Native Multi-Modal Agent Engine |
| License | Proprietary Commercial API (Anthropic Messages API) |
| Input Pricing (per 1M) | $12.00 |
| Output Pricing (per 1M) | $60.00 |