WHERE TO USE SUB-AGENTS VERSUS AGENTS AS TOOLS

Summary from the TLDR Dev newsletter

This article explains when to use sub-agents versus agents as tools when building multi-agent AI systems. The main difference is that agents as tools are self-contained, stateless specialists ideal for discrete tasks (like converting natural language to SQL), while sub-agents are delegated team members that share context and handle complex, multi-step processes requiring ongoing collaboration (like managing flight bookings with multiple user interactions). Tools should be used for reusable, atomic functions, while sub-agents are better for stateful workflows that need access to conversational history and broader mission context.