D&D 5E Detecting concentration?

[Maxperson]

Doesn't the PHB say you can maintain concentration while attacking? This would seem to me that it is rather easy to maintain and does not use too much of your effort.

This. Concentration doesn't really take up much in the way of concentration. Just enough to prevent the casting of another spell that requires it and nothing more. I wouldn't let it be detectable.

 

[Fenris-77]

Doesn't the PHB say you can maintain concentration while attacking? This would seem to me that it is rather easy to maintain and does not use too much of your effort.

Until a Barbarian the size of a Holstein pops you in the teeth with one of his enormous mitts of course. Then you're borked. So I guess it's easy until it's not is the moral of the story.

 

[Umbran]

Concentration allows you to fight, cast other spells, make ability checks, and so on without any modifiers. I am not sure that there should be any visible manifestation of this that the PCs can read.

 

[doctorbadwolf]

Until a Barbarian the size of a Holstein pops you in the teeth with one of his enormous mitts of course. Then you're borked. So I guess it's easy until it's not is the moral of the story.

Eh, depends on the bonus to the save. The barbarian isn't going to do that much damage with a punch.