Politeness measurably affects LLM output quality, but there's no universal effect—different languages and models respond differently to tone, so developers should test politeness strategies for their specific use case and audience.
This study tests how politeness in user prompts affects AI model responses across 5 models, 3 languages, and 22,500 prompt-response pairs. Results show politeness improves response quality by ~11% on average, but the effect varies significantly by language and model—English models prefer politeness, Hindi models prefer deference, Spanish models prefer assertiveness.