Hey Jess,
I remember when music box was implemented and nobody found any kind of "official information" about it, except by the taming item NPC answering to "music box" which indicated it was indeed a taming item. Well, the standard weight of 2 oz and the item description also pointed towards it being a taming item. Then, players started investigating it and discovered which monsters can be tamed with it. There was a test server on which I tried to tame the monsters that are not in the "confirmed list" and they indeed couldn't be tamed, so somebody else had probably checked them before me. However, I can't state I double checked all creatures on the "tamable" list (it would take a few years of test servers to check them all with a single music box). Anyway, in all these tests, the music box never broke.