Please, don't call your character smart

Smart characters are the best, but there's nothing worse than hearing the narrator or characters talk about how smart an MC is, only for them to do nothing smart or clever whatsoever. And as soon as you tell the reader a character is smart, rational actions and even clever moments become requirements in the eyes of your readers. It just makes your life harder.

There's nothing to gain by announcing a character is smart but there's everything to lose. So please don't do it.