Claude Fable 5.1 vs GPT-5.4 Nano
| Anthropic Claude Claude Fable 5.1 | OpenAI GPT-5.4 Nano | |
|---|---|---|
| Vendor | Anthropic Claude | OpenAI |
| Context window | 1,000,000 | 400,000 |
| Max output | 128,000 | 128,000 |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| File input | Yes | Yes |
| Input | text, image, file | text, image |
| Output | text | text |
| Released | 2026-09-01 | 2026-03-17 |