Kimi K3.1 vs GPT-6 Astra on the same agentic 3D task: full token and cost breakdown
GapNew4766 · reddit · 2026-10-24
An open-source agent developer ran the same one-shot task on Kimi K3.1 and GPT-6 Astra: a 28s Avatar-style dragon flight in Three.js with six camera shots, all meshes in code, deterministic frame-by-frame recording.
Key numbers
- K3.1: 12:28 wall time, 20 steps, 23 tool calls, 725K prompt tokens read (94% cache hits), 49.2K output tokens (56% reasoning), 746-line file, $1.1–1.4 estimated
- Astra: 9:17, 35 steps, 35 tool calls, 1.2M prompt tokens (97% hits), 22.2K output tokens (only 1.7K reasoning), 217 lines, $2.63
Structural insight: K3.1 reasons heavily and writes in big chunks — fewer steps means less context re-reading, friendlier to prefill-bound local hardware; but its 2x decode-heavy output means decode speed decides whether local MoE runs take 15 minutes or an hour.
Gotchas: K3.1 only accepts temperature=1; the agent's image-review sub-calls kept 0.2, so both screenshot-review attempts failed and it shipped blind (a sunrise rendered as a flat teal frame). Astra filled every optional tool argument with zeros, causing 29 consecutive shell-tool rejections and a 2.5-minute first-run crash.
Practical tip: to run K3.1 as a local agent, pin temperature to 1 across your whole stack (vision, summaries, sub-calls), not just the main chat call.
Related event: Kimi K3.1 vs GPT-6 Astra tested on same 3D agent task(3 posts)→
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