@JeremyECrawford does the use an object action include using the power of a magic item. Example, I have an item that can cast a spell.

— Justin Thompson (@JustinTdndplay) May 4, 2016

Magic items aren't activated with the Use an Object action (see DMG, 141). #DnD https://t.co/eWapgWmwrR

— Jeremy Crawford (@JeremyECrawford) May 9, 2016

@JeremyECrawford thanks. What action is it to use magic items

— Justin Thompson (@JustinTdndplay) May 9, 2016

The action used to activate a magic item is ad hoc—just like the action used to activate most class features. #DnD https://t.co/J7FqO8Osdp

— Jeremy Crawford (@JeremyECrawford) May 18, 2016