Claude Opus 5.5 (Adaptive Reasoning, Xhigh Effort, Default Fallback)

Claude Opus 5.5 is an artificial intelligence model developed by Anthropic and released on September 17, 2026. The model features an intelligence index of 56 and demonstrates performance across several standardized evaluations, including an HLE score of 0.575, a SciCode score of 0.65, and an LCR score of 0.846666666666667. Regarding operational efficiency, the model provides an output speed of 84.874 tokens per second with a time to first token of 63.684 seconds. Pricing for the model is structured at $4.00 per million tokens for input and $20.00 per million tokens for output, resulting in a blended rate of $8.00 per million tokens. This configuration utilizes adaptive reasoning with high effort and a default fallback setting.