grok-4-fast-non-reasoning vs Claude Fable 5.1
| xAI grok-4-fast-non-reasoning | Anthropic Claude Claude Fable 5.1 | |
|---|---|---|
| Vendor | xAI | Anthropic Claude |
| Context window | 2,097,152 | 1,000,000 |
| Max output | 30,000 | 128,000 |
| Reasoning | No | Yes |
| Tool calling | Yes | Yes |
| File input | Yes | Yes |
| Input | text, image | text, image |
| Output | text | text |
| Released | 2025-08-27 | 2026-08-31 |