OpenAI has released an addendum to the GPT-5 system card, introducing a new model called GPT-5-Codex. This version of GPT-5 is optimized for agentic coding in Codex, allowing it to dynamically adjust its thinking effort based on task complexity. The model can respond quickly to simple conversational queries or small tasks, while working independently on more complex tasks for longer periods. --- Why it matters: This matters because GPT-5-Codex demonstrates a new level of flexibility and efficiency in AI systems, which could have significant implications for applications that require both speed and accuracy. Researchers may be interested in understanding how this model's dynamic thinking effort is achieved and whether it can be applied to other domains. Source: https://openai.com/index/gpt-5-system-card-addendum-gpt-5-codex