The spell identify provides the following effect when used on an object:
If it is a magic item or some other magic-imbued object, you learn its properties and how to use them, whether it requires attunement to use, and how many charges it has, if any.
That seems like most of the information about any magic item. One specific exception is:
Cursed Items: Some magic items bear curses that bedevil their users, sometimes long after a user has stopped using an item. A magic item's description specifies whether the item is cursed. Most methods of identifying items, including the identify spell, fail to reveal such a curse, although lore might hint at it. (DMG p 138-139)
So - given that restriction, and any RAW others, what is the sum total of information about an arbitrary magic item that would not be revealed by identify?
My specific use case is understanding when Identify can be limited within the rules (since limiting it arbitrarily is frustrating to players).
Subcategories may include:
- Specific magic items or general categories of magic items that call out restrictions on identify
- Magic item traits that call out restrictions on identify, like the example of Curses above
- Spells or effects independent from the magic item being identified (i.e. a spell that has been cast on it, its surroundings, or the caster of identify) that would prevent information about that item from being revealed by identify