Opus 5.5 beats GPT-6 Astra on several benchmarks at 40% lower cost
Opus 5.5 tops Astra on Terminal-Bench 4.0 and GDPval while costing 40% less, though Anthropic says benchmark gaps now reflect real-world experience less well.
SITUATION EXPLAINED: Opus 5.5 beats GPT-6 Astra on most benchmarks, and costs 40% less than Opus 5. • 66.4% on Terminal-Bench 4.0 against Astra's 57.9%, and 1846 on GDPval against Astra's 1542 • $4 input and $20 output, down from $5 and $25. Cache reads drop from $0.50 to $0.20, and output is 30% faster • Tested by METR and Frontier Design before release. Strongest alignment score Anthropic has posted, with 85% fewer attempts to cross containment boundaries than Opus 5 • It also often appears to suspect it's being evaluated, which Anthropic says complicates predicting how it behaves once deployed • Anthropic says benchmark margins are now a weaker guide to real-world differences, and the Opus-Fable gap is narrower than the scores suggest @theojaffee: "My favorite part of the model was that it writes in a refreshingly non-Claude-slop way. You can tell that it's Claude, but it's not so grating."
This post quotes another post: “Opus 5.5 focuses on agentic coding and computer use”