Can't turn off GPT-5 Thinking Mini

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This topic might provide a solution, even temporary; in my personal experice it works sometimes:

Need "reasoning: false" option for GPT-5

Hello everyone, We’ve run into a serious limitation while integrating GPT-5 into our product (Translator Pro for Unity – available on the Unity Asset Store). Unlike standard models like gpt-4o, GPT-5 always applies its reasoning layer. That’s fine for complex reasoning tasks, but it breaks simple deterministic workflows such as translation. Example: gpt-4o / gpt-4.1 → returns clean translations. gpt-5 → often just echoes the source (English → English), because reasoning interferes. …