Sub-agent

What is a sub-agent?

A sub-agent is an AI agent that a lead agent assigns part of a task to, with its own instructions and context. The lead agent writes a brief for the sub-agent, which works in a separate context window and returns a summary of its results. Hugging Face's agent glossary notes that a sub-agent can reason on its own, which a tool cannot.

Why it matters to a revenue leader

Sub-agents let AI take on bigger jobs, such as researching a whole list of target accounts, without one agent losing track of the details. They also cost more. Anthropic reported that its multi-agent setup used about 15 times more tokens than a chat, and found that vague briefs led sub-agents to duplicate work or leave gaps, the same failure a manager sees after an unclear handoff. If you pay usage-based AI bills, find out when a tool splits work across sub-agents and what each one is allowed to access.

A utility services company asks an AI tool to profile 40 municipal accounts before budget season. The lead agent splits the list among four sub-agents, each researching 10 accounts, then assembles one brief per account. The research finishes in a fraction of the time, and the usage charge for the job is several times what a single agent would have cost.