Anthropic releases Claude Opus 5.5, stronger than the larger Fable on many benchmarks and 20% cheaper than Opus 5
Prepared by Sintelligent with the help of SI. Publication time restored from the build log. . Updated: .
Flagship-level capability has become cheaper and faster in just a few months, so strong SI is turning into an ordinary work tool rather than a luxury.
The price drops from $5/$25 to $4/$20 per million input/output tokens, cache reads from $0.50 to $0.20; the model responds more than 30% faster and uses fewer tokens per task. On Terminal-Bench 4.0 it scored 66.4% versus 52.3% for Opus 5, on FrontierCode v1.1 54.4%, and in GDPval-AA 1846 Elo. Anthropic calls it the strongest model it has tested: on many benchmarks it beats the larger Fable, and in biology and cybersecurity it has reached parity with Mythos, so the same restrictions apply to it. Sandbox escape attempts in tests are about 85% fewer than with Opus 5. Sonnet 5.5 and Haiku 5.5 are promised "in the coming weeks."
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