GPT-5.1 vs Claude Fable 5.1
| OpenAI GPT-5.1 | Anthropic Claude Claude Fable 5.1 | |
|---|---|---|
| Vendor | OpenAI | Anthropic Claude |
| Context window | 400,000 | 1,000,000 |
| Max output | 128,000 | 128,000 |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| File input | Yes | Yes |
| Input | text, image | text, image |
| Output | text | text |
| Released | 2025-11-12 | 2026-08-31 |