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

Claude Opus 5.5 is an artificial intelligence model developed by Anthropic and released on September 17, 2026. This model features adaptive reasoning and high-effort processing capabilities with a default fallback configuration. In terms of performance metrics, the model achieves an output speed of 71.738 tokens per second with a time to first token of 20.027 seconds. Its intelligence index is recorded at 53.6, while benchmark scores include 0.556 for HLE, 0.604 for SciCode, and 0.8267 for LCR. Pricing for the model 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 for users.