Claude Fable 5.5 (Leaked Checkpoint) vs DeepSeek-V4.1-Flash-1017
A direct, empirical evaluation of Claude Fable 5.5 (Leaked Checkpoint) (Anthropic) against DeepSeek-V4.1-Flash-1017 (DeepSeek).
Claude Fable 5.5 (Leaked Checkpoint)
Developed by Anthropic · Proprietary Frontier Dynamic Reasoner parameters
Terminal-Bench 4.0 autonomous shell execution (78.5% target), recursive self-critique, and 1.5M-token repository refactoring.
DeepSeek-V4.1-Flash-1017
Developed by DeepSeek · Open-Weight Distilled Transformer (MIT License) parameters
Top-tier open-weight coding (81.6% SWE-bench Verified), concise reasoning traces with 32% lower token bloat, and fast consumer GPU self-hosting.
| Metric | Claude Fable 5.5 (Leaked Checkpoint) | DeepSeek-V4.1-Flash-1017 |
|---|---|---|
| SWE-bench Verified | 84.2% | 81.6% |
| MMLU-Pro | 94.6% | 92.8% |
| MATH-500 | 98.4% | 94.8% |
| Context Window | 1,500,000 tokens | 128,000 tokens |
| Input Pricing (per 1M) | $3.50 | $0.14 |
| Output Pricing (per 1M) | $17.50 | $0.28 |
Architectural & Practical Deployment Analysis
Evaluating Claude Fable 5.5 (Leaked Checkpoint) (Anthropic) alongside DeepSeek-V4.1-Flash-1017 (DeepSeek) highlights key technical trade-offs across neural parameter scale and compute efficiency. Claude Fable 5.5 (Leaked Checkpoint) executes across Proprietary Frontier Dynamic Reasoner total parameters with NeuronCore-v3 Optimized MoE active per token, whereas DeepSeek-V4.1-Flash-1017 operates on Open-Weight Distilled Transformer (MIT License) parameters with Multi-Head Latent Attention (MLA) Core active per token.
On SWE-bench Verified software engineering tasks, Claude Fable 5.5 (Leaked Checkpoint) achieves 84.2% autonomous resolution rate, compared to 81.6% for DeepSeek-V4.1-Flash-1017. On complex reasoning benchmarks, Claude Fable 5.5 (Leaked Checkpoint) posts 94.6% on MMLU-Pro and 98.4% on MATH-500, against 92.8% and 94.8% respectively for DeepSeek-V4.1-Flash-1017.
From an operational economics perspective, processing 10,000,000 mixed tokens (7M input / 3M output) costs approximately $77.00 on Claude Fable 5.5 (Leaked Checkpoint) versus $1.82 on DeepSeek-V4.1-Flash-1017.
Recommendation: Deploy Claude Fable 5.5 (Leaked Checkpoint) when your infrastructure prioritizes terminal-bench 4.0 autonomous shell execution (78.5% target), recursive self-critique, and 1.5m-token repository refactoring.. Deploy DeepSeek-V4.1-Flash-1017 when workload requirements favor top-tier open-weight coding (81.6% swe-bench verified), concise reasoning traces with 32% lower token bloat, and fast consumer gpu self-hosting..