OpenAI Launches the GPT-5.6 Series
Don't Worry About the Vase (Zvi) · rss · 2026-07-14
This is an in-depth review of OpenAI's new GPT-5.6 series: Sol, Terra, and Luna. The author suggests that while both Sol and Fable are highly capable, they serve different purposes: Fable acts as a "smarter partner/architect," whereas Sol is the "workhorse that gets things done."
The article also summarizes official claims and community feedback:
- Pricing: Sol is priced at $5/$30, Terra at $2.50/$15, and Luna at $1/$6; comparisons are drawn to Opus and Fable pricing.
- Coding/Agent capabilities: OpenAI highlights benchmarks like Agents’ Last Exam, AA Agent Coding Index v1.1, and BrowseComp, claiming leadership across various tasks.
- Internal usage: OpenAI notes that researchers use GPT-5.6 to accelerate debugging, training system optimization, experiment execution, and result analysis, with rapid growth in internal research-related coding inference and agentic token usage.
- Healthcare evaluation: Officially, GPT-5.6 performs better at lower costs in medical scenarios, with some blind-tested doctors preferring its responses over those written by humans.
- Safety & Bio/Cyber Risks: The article mentions OpenAI touched on safety guardrails but provided limited details.
Overall, the author concludes that Sol excels at "actually getting things done," especially paired with coding/agentic workflows, while tasks requiring higher intelligence and stronger "planning" still lean towards Fable.
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