The brief is a starting point
Your contest brief is the first source of information and inspiration for Designers, so it is very important that you take your time and fill it out as completely as possible. The brief doesn't have to be perfection set in stone - it's a starting point for Designers. Most logos take shape during the contest from a continuous feedback loop between the client and Designers. That said, providing as much relevant information as possible will prevent misunderstandings during your contest.