Claude Opus 5.5 Should Raise Your Ambitions

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• Claude Opus 5.5 represents a significant leap, offering Fable 5.1-level performance at a lower cost, and should “raise your ambition levels” due to its reliability, pleasant interaction, and broad improvements.
• Key advancements include “extremely strong” cyber capabilities, dramatically improved writing quality, enhanced 3D vision, and impressive creative outputs (videos, music), often outperforming Astra on overall intelligence benchmarks.
• Opus 5.5 is recommended as the new default model for most tasks, but users should calibrate thinking levels, reserve Fable 5.1 for expert-domain correctness or “big model smell” (complex philosophical discussions), and be aware of occasional “over-eager” behavior or struggles with deep inference.