Marking Targets - Necessary?

[HoroBoro]

As a damage role often using the dungeon finder, I would like tanks to mark if they intend to switch between targets non stop.

Nothing like attacking the pulled mob, and get aggro 5 secs later. Then click on the tank and hotkey for attack target's target. Then surprise - 10 secs later, getting aggro again because tank decided to switch to a 3rd target.

At least if they mark it, I'll get some warning before switching.

Oh and please check if target is "fully rested" if I try to sleep it. That means... I can't sleep it.