GPT 5.6 Luna: Good, Fast and Cheap
Melvin Vivas · X post · 2026-08-01 · Open on X
Topics: LLM Fundamentals · Level: beginner
Summary
The creator says GPT 5.6 Luna is good, fast and low-cost. It is a quick tip for picking a model when cost and speed matter.
Key points
- GPT 5.6 Luna gives good quality at low latency and low cost.
- Worth considering when speed and cost matter more than maximum capability.
Resources mentioned
- GPT 5.6 Luna · tool · openai.com · paid
The OpenAI model used inside Codex for the demo. The transcript gives the variant name as 'Soul', which is unclear.
Also in: Set Codex subagent model and reasoning to save usage limits (Melvin Vivas on X · notes), Use GPT-5.6 Luna in Codex for Terminal Tasks (Melvin Vivas on X · notes), Match Reasoning Effort to Task Length in Codex (Astra/Sol) (Melvin Vivas on X · notes), Run Coworker desktop agents cheaply with GPT-5.6 Luna on OpenRouter (Melvin Vivas on X · notes) and 24 more
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