Brand
Brand voice is a decision-making tool, not a mood board
A brand voice document that lists three adjectives ('bold, friendly, expert') does not help anyone write the next social caption. A useful voice guide gives examples of what the brand would never say, shows two versions of the same message and explains why one is right, and gets updated after real campaigns, not written once and filed away.
Treat it like a working document your team actually opens before writing, not a PDF from the kickoff meeting.