How important is it to describe physical attributes of characters in a novel? Difficult question really.
Sometimes the information can feel incidental, and other times integral. More often I tend to find, especially when introducing a character, their bearing is more important; how they walk, whether they are menacing, duck-footed, slouching, confident, awkward, smiling, dispassionate and so on. I also find how they dress to provide hints of character – one which grants the reader an ability to make their own first impressions, ideally without being told what to think by the author.
Physical attributes can be important too, especially if they prove integral to the plot, but often it is best to leave such description to a minimum, so the reader can imagine themselves as the protagonist – or so they can be attracted to them. I once read a comment remarking that no-one could ever act a fully satisfactory version of Raymond Chandler’s Phillip Marlowe as he is the reader, or, if the reader happens to be female, Marlowe looks like her ideal man. Obviously that comment doesn’t allow for all sexual preferences but you get the idea. Sometimes it is better to leave the physical appearance of a character in the mind of the reader.