GoKawiilAnthropic launches Claude Opus 5.5, cutting inference costs 40% versus Opus 5
Anthropic released Claude Opus 5.5, the first entry in its 5.5 model family, matching the performance of Claude Fable 5.1 on most tasks while running 40% cheaper than its predecessor, Opus 5. The model underwent external evaluation by groups including Frontier Design and METR, and scored higher than any prior Anthropic model on the company's internal automated behavioral audit for alignment and safety.
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The release signals Anthropic's attempt to balance rapid capability gains with deliberate safety pacing, following its earlier pledge to slow frontier progress. Sharp cost reductions alongside major coding and software-optimization gains suggest AI assistants are becoming both more capable and more economical for enterprise-scale engineering work, intensifying competition with rivals like OpenAI and Google.
- Opus 5.5 costs 40% less to run than Opus 5 while matching Claude Fable 5.1 on most tasks.
- It scored highest ever on Anthropic's automated behavioral audit, showing improved resistance to prompt injection and risky autonomous actions.
- Early testers reported major real-world gains, including a 680,000-line code migration completed in under a day.
Source: anthropic.com, 2026-09-22
Published there as: “Claude Opus 5.5”
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