Brainstorming helps turn ideas into fully formed designs and specs through natural collaborative dialogue before any implementation begins. It starts by exploring project context, asking clarifying questions one at a time, proposing multiple approaches with trade-offs, and presenting sections of the design for user approval. Finally, it guides the agent to write a design doc to disk and transition to the writing-plans skill. Reach for it before undertaking any creative work, creating features, building components, or modifying behavior.