The birthday message problem nobody admits to
Most people type 'Happy birthday! Hope you have an amazing day!' and feel vaguely bad about it. Not because it's wrong — it's perfectly fine — but because it's the same thing seventeen other people will write on the same post. The thing that makes a birthday message memorable is specificity: one detail that only you would include, one reference that proves you actually know this person. This prompt forces that by asking for a specific quality or memory. The AI builds the message around it.
Adjusting tone in the prompt
The tone field does a lot of work here. 'Warm and heartfelt' produces something genuine and emotional. 'Funny and light' produces something that'll make them laugh. 'Short and sincere' produces a single punchy sentence that's better than a paragraph of generic warmth. Pick the one that matches your actual relationship with the person, not the one that sounds nicest.