Claude Opus 5 aims to match or exceed Fable 5's performance on many tasks while being faster and half the price.
Opus 5 shows substantial gains over Opus 4.8 in agentic coding, computer use, and long-horizon knowledge work, setting new state-of-the-art benchmarks.
Opus 5 lacks full 'Juice' for cyber offense and bio threats due to deliberate avoidance of cyber training and smaller model size.
Safety classifiers trigger 85% less often than Fable's, permitting source code vulnerability analysis but blocking binary vulnerability discovery.