Include product context
Explain who the interface is for, the primary task, the target framework, and the most important action. This gives the model a hierarchy instead of a list of visual decorations.
Describe behavior
Mention loading, empty, error, hover, focus, selected, and mobile states when they matter. Static prompts tend to produce static results.
Constrain the implementation
Specify framework, styling approach, accessibility expectations, dependency preferences, and whether components should be reusable. Clear constraints reduce unnecessary rewrites.