Pyyan / Compare / GPT-5.6 Luna vs Claude Fable 5
GPT-5.6 Luna vs Claude Fable 5
2 of 5Language Models · verified 13 Aug 2026
GPT-5.6 LunaOpenAIcurrentClaude Fable 5Anthropiccurrent
| Specification | GPT-5.6 Luna | Claude Fable 5 |
|---|---|---|
| Summary | Fastest and cheapest GPT-5.6 tier. | Most capable widely released model, for the hardest reasoning and long-horizon agentic work. |
| Context | 1M+ | 1M |
| Input ($/Mtok) | — | $10 |
| Output ($/Mtok) | — | $50 |
| Licence | Proprietary | Proprietary |
| Max output | — | 128K |
| Model ID | — | claude-fable-5 |
| Category | Language Models | Language Models |
| Official | OpenAI ↗ | Anthropic ↗ |
Highlighted rows are where these differ.
Claude Fable 5
- Thinking is always on — the `thinking` param is rejected
- Raw chain of thought is never returned
- Requires 30-day data retention; unavailable under ZDR
Best for the hardest problems.