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

Claude Opus 5.5 is an artificial intelligence model developed by Anthropic and released on September 22, 2026. This model features adaptive reasoning, max effort, and default fallback capabilities. In terms of performance metrics, the model holds an intelligence index of 57.6. Benchmark results for the model include an HLE score of 0.614, a SciCode score of 0.669, and an LCR score of 0.846666666666667. Regarding cost, the pricing structure for Claude Opus 5.5 is set 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. Specific data regarding coding index, math index, output speed, and time to first token remains currently unknown.