| 2 models | Cl Anthropic Claude Fable 5 View → | Op OpenAI GPT-5.5 View → |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Tier | Flagship | Flagship |
| Status | Active | Default |
| Context window | 1M ctx | 1M ctx |
| Knowledge cutoff | Jan 1, 2026 | Jan 1, 2026 |
| Released | Jun 9, 2026 | Apr 23, 2026 |
| API string | claude-fable-5 | gpt-5.5 |
| Note | First publicly available Mythos-class model (above Opus); Mythos 5 weights with safety classifiers active. 1M context, $10/$50, highest benchmarks of any GA model. Refusals return stop_reason refusal; mandatory 30-day retention. |
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