ID of the node that spawned the subagent
Unique ID of this spawn; matches the finished event
Start time, Unix timestamp in seconds
Goal assigned to the subagent
Full task prompt given to the subagent
Subagent identifier; may be omitted
Tools granted to the subagent; may be omitted
Payload of a
subagent_startedstream event. When the Agent spawns a subagent to work on a sub-task, the subagent's lifecycle is reported with this dedicated event family instead ofnodeToolUse*.