Writing for the right age band
A one-year-old and a seven-year-old need different songs. Toddlers, roughly one to three, respond to heavy repetition and very simple words, a single idea repeated in almost every line. Preschoolers, three to five, can follow counting, daily routines and animal sounds, and enjoy a short call-and-response. Early school kids, five to eight, can handle a little story with a beginning and an end, plus sillier wordplay and rhymes they can predict.
Say the age band directly in the prompt along with the child's name and one or two favorite things, a dinosaur, a bicycle, a stuffed rabbit. For unusual names or nicknames, spell them phonetically so the generator sings them correctly, and ask for the name to repeat often; kids notice their own name in a song faster than almost anything else in the lyric.