Marked for Death, bugged or working as intended?

Often when I get abilities I don’t fully understand what they do from the tooltip, main issue is I just want to know the cost of the abilities which are not listed in the training tab

Marked for death was a particularly disappointing 25sp cost ability for me, currently when you mark an enemy for death you do any actions afterwards, even though the ability costs 0 ability points. So the first time I used it I had it on my sniper, who I had already upgraded so she could shoot 2 shots a turn, I figured I would mark an enemy for death, get a guaranteed kill and take another shot. However after I marked an enemy when I selected my pistol or my sniper rifle it told me the qualifications were not met or something.

If this was intended as a spotter type ability it needs to be clearly labeled and if it isn’t intended I look forward to it being fixed.

Also updating the tool tips for the abilities really needs to happen, we should know how many will points and ability points a new perk will cost us in battle before we buy it.

Also on the subject of tool tips, the perk ‘Expert Rifles and Handguns’ says it helps rifles and handguns, does that include sniper rifles? I’m still not sure.