Anthropic releases Claude Opus 5.5

Anthropic/Claude models

Anthropic released Claude Opus 5.5, the first model in its 5.5 family, which it says performs at the level of Claude Fable 5.1 on most work and costs about 40% less to run than Opus 5. Because it is comparable to Mythos 5.1 in biology and cybersecurity, it ships with Fable 5.1-level safeguards in those areas. Sonnet 5.5 and Haiku 5.5 are due in the coming weeks.

• Price: $4/$20 per million input/output tokens (Opus 5: $5/$25); cache reads $0.20, down 60%
• Beats Fable 5.1 on Terminal-Bench 4.0 (66.4% vs 55.8%) and FrontierCode (54.4% vs 50.3%)
• OSWorld 2.1 computer use 81.8% vs 80.7%; output about 30% faster than Opus 5
• Most sensitive cyber tasks are routed to Opus 4.8; vetted users can get fuller access via verification programmes
• 85% fewer attempts to get around containment boundaries than Opus 5, per Anthropic's audit