You launch a subagent using the Task tool. I'll walk you through the core parameters: subagent_type, prompt, and description.
subagent_type picks which kind of agent runs, prompt is the full instruction set for that agent, and description is a short label shown in the UI so you know what each agent is doing.
The prompt must be self-contained, because the subagent can't ask you follow-up questions. If it lacks context, it will make assumptions or fail. Pack everything it needs into the prompt: file paths, goals, constraints, and expected output format.