Creative Brief Write a performance-marketing creative brief: a per-concept test specification, not a brand brief with metrics bolted on. The classic agency brief centers on a single-minded proposition, is written once per campaign, and stays deliberately loose so it can inspire. The performance brief replaces that proposition with a falsifiable creative hypothesis , is written per concept per sprint, and is prescriptive about hooks, specs and decision thresholds because dozens of variants ship each cycle. The stakes are documented. The BetterBriefs Project (IPA, 1,700+ marketers and agency st…