Claude Fable 5.1 (Adaptive Reasoning, High Effort, Default Fallback)

Claude Fable 5.1 is an AI model developed by Anthropic, released on September 1, 2026. Designed with adaptive reasoning and high-effort processing capabilities, the model serves as a default fallback option. In terms of performance metrics, Claude Fable 5.1 achieves an intelligence index of 62.5 and a coding index of 79.1. Benchmark results for the model include a GPQA score of 0.906, an HLE score of 0.559, a SciCode score of 0.576, and an LCR score of 0.77. The model operates at an output speed of 61.39 tokens per second with a time to first token of 16.069 seconds. Pricing is set at $10.00 per million input tokens and $50.00 per million output tokens.