Name the change
A useful brief starts with what should be different after the work. That might be how quickly a customer understands the offer or how consistently a team can launch new features.
Separate facts from assumptions
Mark what the team knows, what it believes and what still needs testing. This keeps research focused and prevents an inherited opinion from becoming an invisible constraint.
Make decisions visible
List who decides, who contributes and what evidence will move the project forward. Clarity here creates more creative freedom later.