OpenAI: GPT-5.6 Luna Pro
OpenAI's flagship model. Long-context specialist with 1.1M window.
Scores by test
Methodology →What you need to know
GPT-5.6 Luna Pro is a high-precision model optimized for strict adherence to formatting and complex reasoning. It achieves perfect scores in structured output, constrained rewriting, and strategic analysis, making it a reliable choice for workflows where output validity and logical rigor are non-negotiable. Its ability to maintain high faithfulness and persona consistency across a 1.1M token context window allows for the processing of massive datasets without losing coherence.
At a blended cost of $4.75/MTok, this model sits in a premium price tier. While the output cost is six times higher than the input cost, the pricing is justified by its top-10 overall rank and near-perfect internal scoring. It provides a high level of reliability that reduces the need for expensive prompt engineering or multi-step verification pipelines.
The model shows slight relative weaknesses in classification, tool calling, and safety calibration, though these remain strong at 4/5. These are not failures, but rather areas where it performs slightly below its peak capabilities in structured reasoning and long-context analysis.
Use this model if your application requires absolute precision in structured data, complex strategic planning, or the analysis of very large documents. Skip this model if you are building a simple classification tool or a high-volume agent primarily reliant on tool calling, as the premium cost outweighs the marginal utility for those specific tasks.
Strengths — Top 3
Relative weaknesses — Bottom 3
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