Grooming is often treated as an optional refinement step. In BMAD it is mandatory, because AI agents do not ask clarifying questions the way a human developer would. A human developer reading an ambiguous story might ask "does this mean X or Y?" before starting. An AI will pick one interpretation and implement it. If it picked the wrong one, the work needs to be redone.
The grooming session takes a story from "written" to "ready." Ready means: the acceptance criteria cover both success and failure paths; the scope is appropriate for a single session; all dependencies are identified and either satisfied or explicitly flagged; and any term in the story that could be interpreted more than one way has been resolved before implementation begins.
BMAD supports several grooming patterns — Party Mode, Sequential Grooming, and Scope Hammering — each suited to different kinds of ambiguity and team contexts. All produce the same output: a story that is unambiguous, correctly sized, and ready for a single-session implementation. The right pattern depends on how much ambiguity the story contains and how many perspectives are needed to resolve it.