Anthropic's Claude Opus 5.5 Debuts at No. 1 on Artificial Analysis

Anthropic introduced Claude Opus 5.5 on September 22, 2026. Artificial Analysis lists the Adaptive Reasoning, Max Effort, Default Fallback configuration at No. 1 of 206 models with an Intelligence Index score of 58. The listing credits Anthropic and notes text and image input, text output, reasoning, and 1M-token context.