OpenAI released GPT-6 Astra, a new model competing with Anthropic's Claude Fable 5, available to ChatGPT Plus/Pro/Business/Enterprise users and via API at $10/million input and $50/million output. The model demonstrates exceptional performance on security tasks (100% on ExploitBench, 99.2% on SRE-Bench), strong long-context capabilities, and a notable 99.9% score on ARC-AGI 3 — though that result used a custom harness. It matches GPT-5.6 Sol on OpenAI's Intelligence Index but still trails Fable on Artificial Analysis's Intelligence Index.
Background
OpenAI continues its model iteration cycle with GPT-6 Astra, entering direct competition with Anthropic's Claude Fable 5 series in the flagship AI model market.
- Source
- Simon Willison
- Published
- Sep 4, 2026 at 04:18 AM
- Score
- 8.0 / 10