Artificial Intelligence (AI) is reshaping the landscape of product interaction design, yet its integration into iterative design processes remains underdeveloped. This study introduces the Inspirational Stimuli Toolkit for AI-Powered Products (ISfAI), a medium-level stimuli toolkit designed to support the ideation and evolution of intelligent product interactions. By providing structured and context-aware stimuli, ISfAI enables designers to explore the affordances of AI technologies and translate them into meaningful user interactions. An empirical investigation involving 21 senior industrial design students was conducted through questionnaires and practice-based design tasks. Results demonstrate that ISfAI significantly enhances iterative refinement by fostering divergent thinking, improving understanding of AI’s human-centered functions and capabilities, and advancing design outcomes across dimensions of novelty, usefulness, creativity, elaboration, and flexibility. This study offers valuable insights into how domain-specific medium stimuli can support the iteration and innovation of AI-powered products, providing a practical toolkit for creating more intelligent, responsive, and user-centered interactions.