A subagent is a helper agent that a main agent hands a subtask to. It works with its own context and returns only the result.
Example
The main agent plans a report and sends out three subagents, each analysing one source.
For pros
Subagents keep the main agent's context window lean and can run in parallel. Coding tools let you define subagents with their own instruction and limited tools. More agents also mean higher token costs and more points of failure.
