Anthropic Releases Claude Opus 5.5: Fable 5.1-Level Performance at 40% Lower Running Cost Than Opus 5

Anthropic launched Claude Opus 5.5, the first model in its Claude 5.5 family. The team says it matches Fable 5.1 on most work while costing 40% less to run than Opus 5. It leads Anthropic's internal benchmarks on agentic coding, computer use, and knowledge work. It's not a clean sweep—GPT-6 Astra still leads on Terminal-Bench-Science and AutomationBench. Pricing is $4 per 1M input tokens, $20 per 1M output tokens, and cache reads drop to $0.20, a 60% cut that matters most for agentic and coding costs. Output is over 30% faster than Opus 5, with a fast mode offering 2.5x speed. The model is API-only, no open weights. One early tester migrated 680,000 lines of code in under a day.

Why it matters: Anthropic flagship model refresh with 40% cost reduction and Fable 5.1-level performance — a same-day must-write. Held below 92 because the source is a MarkTechPost relay without a direct official blog link or pricing breakdown.