@chr for art commissions, what's expected text-wise is usually basic info like the characters name, height, and gender

visually what is expected is a simpler version of what's called a "turnaround sheet" in the animation biz. It's a front, back, and side view of the character so the artist understands how the character should look in different angles

P.S. if the character has Very Specific Colors that NEED to be used, please include a color palette somewhere, it can be scribbles or splotches