Alright, I am going to answer you instead of the GM but take it with a grain of salt seeing as it is his decision. A description is sometimes better than a picture. A picture can't tell half as much as a description can. In most of the roleplays I have been in, the Gm would prefer a description over a picture any day. Descriptions do three things. 1. They add detail and depth to character more than a picture does. 2. They show your writing abilities especially your descriptive writing abilities. 3. They provide the Gm and everybody also more to go on then just a picture will.