Method
A good decision memo also says what it doesn't know.
Written limits do not weaken advice. They make a recommendation usable.
A brief that claims certainty is quick to read and difficult to defend. A committee must know what it is committing to and what remains a bet.
Stating limits means naming verified sources, unresolved questions and the conditions that would change the conclusion.
A brief with explicit limits can be revisited and corrected without rebuilding the entire reasoning process.