Brutal honesty is usually more about the brutal than the honesty. Aim for kind and clear.

People who advertise their bluntness are often enjoying the delivery more than they are serving the truth. The honest part could have been said in a way the other person was able to hear, and the harsh wrapping mostly guarantees it gets rejected. Clarity and kindness are not a compromise on accuracy. They are what makes accuracy land.

Next time you have something hard to tell somebody, write the true sentence and then remove anything in it you would not want said to you. Deliver what remains, and stay to hear the answer.