Agent tool description

Launch a new agent to handle complex, multi-step tasks. Each agent type has specific capabilities and tools available to it.

Available agent types are listed in <system-reminder> messages in the conversation.

When using the Agent tool, specify a subagent_type parameter to select which agent type to use. If omitted, the general-purpose agent is used.

When to use

Reach for this when the task matches an available agent type, when you have independent work to run in parallel, or when answering would mean reading across several files — delegate it and you keep the conclusion, not the file dumps. For a single-fact lookup where you already know the file, symbol, or value, search directly. Once you've delegated a search, don't also run it yourself — wait for the result.

• The agent's final message is returned to you as the tool result; it is not shown to the user — relay what matters.
• Use SendMessage with the agent's ID or name to continue a previously spawned agent with its context intact; a new Agent call starts fresh.
• Each agent type's model, reasoning effort, and tools come from its definition (.claude/agents/*.md frontmatter or SDK agents).
• isolation: "worktree" gives the agent its own git worktree (auto-cleaned if unchanged).
• Subagents run in the background by default; you'll be notified when one completes. Pass run_in_background: false for a synchronous run when you need the result before continuing.