How Opus 5.5 and Astra model physics when generating animations

Žiga Kovačič @zzigakovacicOriginally posted 2026.10.06

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How do agents model dynamics? We analyze agents' design choices and find their approaches differ substantially. Across solutions, 67% describe motion analytically, 19% implement custom simulations, 10% use Blender physics, and 3% rely on keyframing. Opus 5.5 simulates in 76% of its solutions, while Astra does so far less often, with 13% at Low, 22% at High, and 32% at Max reasoning. [5/n]