GPT-6 Astra ties Claude Fable 5.1 on the Intelligence Index at about 40% of the cost per task, with 2.5x higher token prices offset by far lower token use. Informs model and budget choices for coding agents.
Key takeaways · AI-distilled
On the Intelligence Index, Artificial Analysis says GPT-6 Astra (max) scores 53, matching Claude Fable 5.1 at $3.26 versus $7.63 per task, because it uses about 27k output tokenThe chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.Full definition → per task against Fable 5.1's 78k; every Astra effort level sits on the cost frontier.
In the Coding AI agentAn AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.Full definition → Index, Astra in Codex scores 62 like Fable 5.1 in Claude Code, at $7.09 per task, about 40% cheaper; its 7-point gain over GPT-5.6 Sol comes from Terminal-Bench and SWE-Atlas-QnA, partly offset by a lower DeepSWE score (68% vs 72%).
Astra's drop in AA-Omniscience hallucinationWhen a model states something false with full confidence — inventing facts, citations, or APIs that don't exist.Full definition → rate, from 92% to 51% at max effort, came with a 4-point accuracy gain, which Artificial Analysis notes is not always the case when models hallucinate less.
Not every result improved: Astra lost about 45 Elo on GDPval-AA v2 versus GPT-5.6 Sol, using 24 turns per task against 45 for Sol and 60 for Fable 5.1, and its AA-Briefcase gain of about 90 Elo came with lower Presentation Quality Elo.
Terms in this piece · Glossary
AI agent — An AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.
hallucination — When a model states something false with full confidence — inventing facts, citations, or APIs that don't exist.
token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
