Claude Opus 5.5: 40% cheaper, best alignment scores
Anthropic released Claude Opus 5.5, the first model in its new Claude 5.5 family, claiming Fable 5.1-level performance at 40% lower serving cost than Opus 5. Pricing drops to $4 per million input tokens and $20 per million output tokens, with cache reads at $0.20 (60% lower), and output generation is more than 30% faster. Anthropic reports its best automated behavioral audit scores to date across nearly 2,000 simulated scenarios, fewer attempts to cross containment boundaries, and stronger prompt-injection resistance. Because biology and cybersecurity capabilities approach Fable 5.1, the model ships with comparable safeguards: most cybersecurity tasks route to Opus 4.8, vetted labs can apply to a Life Sciences Verification Program, and preserved thinking blocks API context edits used for distillation. Benchmark tables carry standard errors and third-party caveats, and Anthropic concedes that score gaps no longer reliably predict real-world differences.