The layout tool is still a work in progress. You can activate it from the modes panel.
By pressing the shift key and dragging in the viewport you will be able to select agents (no need to click any mouse button). For every selected agent you will be able to see its agent ID and agent type.
This is currently the only way to find the agent ID of an agent, you will need agent IDs when applying overrides on your agent group modules.
Placing and editing of agents is possible, but we are still working on this area and it will be covered later.