It's common, when reading an amateur screenwriter's work to see the protagonist described using what I like to call the APB method. Here the author takes the idea of visual story telling a little to literally and feels the need to describe the protagonist solely as we would see him or her--to the point where we have a definite picture in our mind of the character and could even pick him or her out of a line-up, hence the All Points Bulletin.
While this might work in literature, where the movie is in our head, in a motion picture the movie is cast with real people, who are going to have a little more trouble changing their physical appearances to fit your APB (unless we're talking about Ron Pearlman). Not only that, but you don't want to write up a character description so specific that it is going to rule out a potential star like Leonardo DiCaprio or Angelina Jolie.
The challenge becomes striking a balance between the physical and the abstract, creating a character that has a definite physical presence and persona, but could be played by anyone. The common adage is that a character description has to serve as actor bait. To craft a character description that achieves this goal there are a few things to keep in mind:
