When a model struggles with a medium, give it a notation. Simon Willison wanted to know if Claude Opus 5.5 could compose, so he didn't ask for a song. He asked it to design a simple text format for music, build a player for it and write tracks aiming for the quality of The Secret of Monkey Island.
It did all three, and he calls the results surprisingly good. The format is the clever bit: music becomes something a model can reason about line by line and a person can open and edit by hand. He's now asking whether composition is a new capability for text models.
