Stemming from this question's answers, there seems to be ambiguity if a magic item being used for an improvised attack is a magical attack.
The PHB describes an improvised weapon as:
Sometimes characters don’t have their Weapons and have to Attack with whatever is at hand. An Improvised Weapon includes any object you can wield in one or two hands, such as broken glass, a table leg, a frying pan, a wagon wheel, or a dead Goblin.
Often, an Improvised Weapon is similar to an actual weapon and can be treated as such. For example, a table leg is akin to a club. At the GM’s option, a character proficient with a weapon can use a similar object as if it were that weapon and use his or her Proficiency Bonus.
Is the improvised weapon attack with a magic item considered a "magical improvised weapon" if it doesn't fall into the second descriptor of being "similar to an actual weapon"?
Some similar, but not exactly the same, questions have been asked, such as attacking with magical gauntlets.