Claude Opus 5.5 (EU)

MarkTechPost confirms Anthropic released Claude Opus 5.5 as the first model in its new Claude 5.5 family, performing at Claude Fable 5.1 level on most work while costing 40% less to run than Opus 5 on typical workloads at default settings. On Anthropic's own benchmarks, the model leads in agentic coding, computer use, Benchmark scores reported use adaptive thinking at maximum effort with production safeguards enabled, with Opus 5.5 achieving 66.4% on Terminal-Bench 4.0, 54.4% on FrontierCode v1.1, 57.8% on CursorBench 4.0, an Elo of 1846 on GDPval-AA v2.1, 81.8% partial credit on OSWorld 2.0, 58.7% on Terminal-Bench-Science 0.1, and

Reuters reports that Anthropic launched Claude Opus 5.5 on September 22, 2026, positioning it as delivering performance comparable to Anthropic's top-tier Fable 5.1 while costing roughly 40% less to run than its predecessor Opus 5. The company stated Opus 5.5 outscored OpenAI's GPT-5.6 Sol on a software development ben Anthropic noted that Opus 5.5 underwent external safety testing by independent groups Frontier Design and METR prior to release and incorporated safeguards previously reserved for its most capable systems. Internal evaluations indicated Opus 5.5 was approximately 85% less likely than Opus 5 or Mythos 5.1 to attempt byp

The Decoder reports that Claude Opus 5.5 is the first model in a new Anthropic family, matching Claude Fable 5.1 performance on most tasks while costing approximately 40 percent less to run than Opus 5, with lower token usage further cutting operating costs. Anthropic's published benchmarks show Opus 5.5 ahead of Fable The release addresses customer feedback on cost, efficiency, and communication quality, particularly in financial services, law, and software, with Anthropic promising to reduce the so-called "Claudish" writing style. Additional restrictions target model distillation, and the rollout supports compliance with the EU AI