Built in
The model chooses when to delegate. Several run at once, up to five. A sub-agent never asks you anything.
Your own
One markdown file per agent under.hum/agents/, scanned recursively. Files in .claude/agents/ and .codex/agents/ are read the same way, and ~/.hum/agents/ holds your personal ones. The nearest file wins a name.
The body is the agent’s role, given to it whole. An agent whose tools can edit is refused while approvals are on.