Subagent
Subagent
Also called: 子智能体 · Sub-agent
An agent spawned by a parent agent to handle one bounded subtask, with its own context window and tool permissions, returning a result to the parent.
Why it exists
Two main motivations:
- Protect the parent context — hand work that reads in a lot of intermediate material (crawling a codebase, scanning a dozen web pages) to a subagent, so the parent receives only a condensed conclusion instead of a context full of noise.
- Isolation and specialisation — give the subagent its own system prompt and a narrower tool set so it stays focused on one job, and its mistakes do not pollute the main flow.
Difference from a plain tool call
A tool call is one deterministic function execution. A subagent is a full agent loop — it reasons, calls tools multiple times, self-corrects, and only then returns. Think of it as "a tool you can outsource a whole task to."
Common misconceptions
- A subagent does not share the parent's context; it sees only the input the parent explicitly passes it.
- More subagents is not necessarily faster: spawning, waiting, and merging all cost time.
Related terms
Sources
Compiled 2026-08-29 · This glossary is compiled from public papers, official specifications, and common industry definitions, and is updated as the field evolves. Corrections welcome.