Breaking

OpenAI Releases GPT-6 Astra, Setting Up a Head-to-Head With Claude Fable 5.1

September 4, 2026 at 05:43 EDT

Foundation Models
AI Agents
Software Dev & Coding

OpenAI has released GPT-6 Astra two days after Anthropic made Claude Fable 5.1 generally available, setting up a direct comparison between two frontier models aimed at coding, long-running agents, and professional computer use.

SEPTEMBER 2026 · FRONTIER MODELS

Astra Meets Fable 5.1

OpenAI's GPT-6 Astra and Anthropic's Claude Fable 5.1 now meet in a close, workflow-dependent contest for coding, agentic work, and computer use.

TERMINAL-BENCH SCIENCE 0.1 · PUBLISHED SCORES

Astra leads this research-agent test

The launch data puts Astra ahead, while independent scoring remains close.

GPT-6 Astra
64.6%

Claude Fable 5.1
52.6%

Each column is scaled to the score; the comparison is vendor-reported and setting-dependent.

THE BILLING SNAPSHOT

$10base input per 1M

$50base output per 1M

1Mshared context tokens

$0.25Fable cache read per 1M

Where the models differ

Astra advantage

Direct software control, browsing, coding, and professional workflows.

Fable 5.1 advantage

Long-running agents, research, code review, and cache-heavy economics.

CAPABILITY AND CONTROL

Both models push autonomy forward.

Astra reaches OpenAI's Critical cybersecurity threshold. Fable 5.1 allows vulnerability discovery but redirects exploit development and other dual-use work behind stronger safeguards.

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