OpenAI has launched the GPT-5.6 series, featuring three models: Sol (flagship), Terra (balanced), and Luna (cost-efficient). The flagship Sol model achieves a state-of-the-art score of 7.8% on the ARC-AGI-3 benchmark, becoming the first verified frontier model to beat an ARC-AGI-3 game. This release marks a significant leap in AI reasoning and agentic capabilities, particularly on the challenging ARC-AGI-3 benchmark that measures interactive reasoning and adaptation. The GPT-5.6 series strengthens OpenAI's competitive position against rivals like Anthropic's Fable 5, and the introduction of max/ultra reasoning, multi-agent collaboration, and Programmatic Tool Calling enables more efficient complex task execution. The GPT-5.6 series includes Sol, Terra, and Luna models, with Sol being the most capable. GPT-5.6 Sol sets a new SOTA on ARC-AGI-3 at 7.8% using max reasoning effort, and also improves performance on coding, science, and cybersecurity tasks. The developer guide highlights improved intent understanding and image detail preservation, while GPT-5.4 is scheduled to be deprecated on July 23.
Background
ARC-AGI-3 is a benchmark designed to evaluate fluid adaptive efficiency and agentic intelligence through interactive, turn-based environments. Unlike its predecessors ARC-AGI-1 and 2, which measure passive reasoning, ARC-AGI-3 requires agents to explore, infer goals, and plan actions without explicit instructions. The GPT-5.6 series builds on OpenAI's previous models, introducing three tiers to balance capability, cost, and speed, and includes features like multi-agent collaboration and programmatic tool calling.
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Discussion
Community comments focus on the developer guide's tips for using GPT-5.6, the SOTA ARC-AGI-3 result, and comparisons with competing models. One user notes that the model beats ARC-AGI-3 games for the first time, while another questions whether Codex can replace Claude Code. A user also highlights that OpenAI excluded Fable 5 from comparisons in certain benchmarks because it refuses many biology questions.