There's a subtle blend of straight and kind. Whatever the thing you have to say, if you have that person interest in mind it's still kind, even if it's tough.
Or rather, in order to TRULY have someone else's interest in mind, you have to incorporate things like condescension as in-scope requirements for your communication. Otherwise, even good advice delivered in a straightforward but condescending manner, won't get through (which means, the person won't benefit, which means you the speaker failed to achieve the thing that would help advance their interest due to your poor communication).