GPT-5 system card addendum: GPT-5-Codex optimized for agentic coding

AI Impact Summary

The introduction of GPT-5-Codex represents a significant shift in the capabilities of the GPT-5 system, specifically tailoring it for agentic coding workflows. This dynamic adjustment of thinking effort – prioritizing speed for simple tasks and sustained focus for complex coding challenges – could dramatically improve developer productivity. Teams should evaluate how this new model’s behavior aligns with existing coding processes and workflows, particularly regarding task decomposition and iterative development.