{"slug": "openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in", "title": "OpenAI Releases GPT-5.6 (Sol, Terra, Luna): A Three-Tier Model Family With Programmatic Tool Calling in the Responses API", "summary": "OpenAI released GPT-5.6 on July 9, 2026, introducing a three-tier model family (Sol, Terra, Luna) with tiered pricing and Programmatic Tool Calling that runs model-written JavaScript in an isolated V8 runtime. The new models achieve competitive coding benchmarks but trail rivals like Claude Fable 5 and Claude Mythos 5 in intelligence and software engineering evaluations.", "body_md": "OpenAI moved GPT-5.6 to general availability on July 9, 2026, shipping three tiers instead of one model. Sol is $5/$30 per 1M tokens, Terra is $2.50/$15, and Luna is $1/$6. Sol sets the Artificial Analysis Coding Agent Index at 80, 2.8 points above Claude Fable 5, and reaches 62.6% on OSWorld 2.0 using 85% fewer output tokens than Opus 4.8. The substantive developer change is Programmatic Tool Calling, which runs model-written JavaScript in an isolated V8 runtime to orchestrate tools without returning every intermediate result to the model. Clio reports a 38% cut in prompt tokens, PlayCo 63.5% fewer total tokens. The gaps are real too: Fable 5 still leads the Artificial Analysis Intelligence Index, GDPval-AA v2, and Toolathlon, and Claude Mythos 5 leads SWE-Bench Pro by roughly 15 points.\n\nThe post [OpenAI Releases GPT-5.6 (Sol, Terra, Luna): A Three-Tier Model Family With Programmatic Tool Calling in the Responses API](https://www.marktechpost.com/2026/07/09/openai-releases-gpt-5-6-a-three-tier-model-family-with-programmatic-tool-calling/) appeared first on [MarkTechPost](https://www.marktechpost.com).", "url": "https://wpnews.pro/news/openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in", "canonical_source": "https://www.marktechpost.com/2026/07/09/openai-releases-gpt-5-6-a-three-tier-model-family-with-programmatic-tool-calling/", "published_at": "2026-07-09 20:45:42+00:00", "updated_at": "2026-07-09 20:52:19.903529+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-products", "ai-tools", "ai-infrastructure"], "entities": ["OpenAI", "GPT-5.6", "Sol", "Terra", "Luna", "Claude Fable 5", "Claude Mythos 5", "Artificial Analysis"], "alternates": {"html": "https://wpnews.pro/news/openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in", "markdown": "https://wpnews.pro/news/openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in.md", "text": "https://wpnews.pro/news/openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in.txt", "jsonld": "https://wpnews.pro/news/openai-releases-gpt-5-6-sol-terra-luna-a-three-tier-model-family-with-tool-in.jsonld"}}