You're describing self-documenting code. Well written code shouldn't require any "what" comments, only "why" comments.
Too often you see code with a generically-named function/variable, and a comment next to it describing what it does. Why not just name the function/variable correctly?!
There's a strong cargo-cult idea that "real" programmers use short/abbreviated names, and yet there's absolutely no value to using "idx" over "index", or a more appropriately named "last_name_index".