Deezer has deployed an automatic playlist captioning system powered by large language models to enhance its Daily Mix feature. This technology generates natural language descriptions for personalized playlists, helping users understand the content behind each recommendation. The system leverages recent advances in LLMs to process diverse data sources while maintaining strict control over output quality. It is now active for millions of users, significantly improving overall engagement metrics. The deployment highlights how semantic framing influences user perception in online personalized experiences. This initiative addresses the challenge of scaling playlist description generation effectively.