Anthropic releases Claude Opus 5.5 with lower costs and external safety testing

Anthropic released Claude Opus 5.5, the first model in its Claude 5.5 family, stating it matches Claude Fable 5.1 performance on most tasks while costing approximately 40% less to run than Opus 5, with input/output pricing at $4/$20 per million tokens. The model underwent external pre-release evaluation and represents the company's first major release after calling for industry pacing of frontier development, emphasizing efficiency gains in agentic coding and professional workloads.