Claude Opus 5.5 Ranks First Among 206 AI Models

Anthropic released Claude Opus 5.5 on September 22, 2026. Artificial Analysis ranks its Adaptive Reasoning, Max Effort, Default Fallback setup No. 1 out of 206 models, with an Intelligence Index score of 58. The listing, credited to Anthropic, notes text and image input, text output, reasoning ability, and 1M-token context window (working memory).