GPT-6 Astra reviews: half the per-task cost, but CoT monitoring breaks down
vista8 · x · 2026-09-04
Latent Space's long-form review roundup of OpenAI's GPT-6 Astra:
- Capability: Coding agent performance is on par with Claude Opus 5 and Fable 5, but behind Fable 5.1; some composite-intelligence dimensions trail GPT-5.6. Strengths are token efficiency, Computer Use, autonomous software engineering, and long-horizon tasks; breakthroughs in 3D modeling (Blender/Unreal) and math reasoning, solving a Lean-verified open Erdős problem.
- Harness controversy: ARC Prize found ARC-AGI-3 hits 99% only on OpenAI's custom harness vs. 63% on standard harness — future evals must disclose proprietary harnesses.
- Safety: Without visible CoT, autonomous runtime jumps from 3.6 to 30.9 minutes, weakening chain-of-thought monitoring.
- Launch: 36M views and 164K likes in 9 hours, the first OpenAI launch to out-hype Anthropic's.
- Pricing: $10/$50 per million input/output tokens ($20/$100 for 2.5x-speed Fast). Per-token price is 2.5x GPT-5.6 Sol, but coding tasks use 1/3 the tokens, halving per-task cost.
Related event: OpenAI launches flagship GPT-6 Astra to rave reviews and pricing debates(190 posts)→
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