Claude Fable 5.5 (Leaked Checkpoint) vs GPT-6.1 Sol
A direct, empirical evaluation of Claude Fable 5.5 (Leaked Checkpoint) (Anthropic) against GPT-6.1 Sol (OpenAI).
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.
GPT-6.1 Sol
Developed by OpenAI · Proprietary Frontier Workhorse Engine parameters
Near-Astra reasoning at 1/5th price ($1.25/$5.00), SWE-bench Verified 74.8%, OSWorld 2.0 desktop agent automation, and sub-80ms Ultrafast Mode.
| Metric | Claude Fable 5.5 (Leaked Checkpoint) | GPT-6.1 Sol |
|---|---|---|
| SWE-bench Verified | 84.2% | 74.8% |
| MMLU-Pro | 94.6% | 92.4% |
| MATH-500 | 98.4% | 96.2% |
| Context Window | 1,500,000 tokens | 1,000,000 tokens |
| Input Pricing (per 1M) | $3.50 | $1.25 |
| Output Pricing (per 1M) | $17.50 | $5.00 |