Okay kiddo, do you know what a spy is, like James Bond? Well, sometimes, in the animal world, some creatures act like spies too! They try to figure out who is a friend and who is a foe. That's what we call "agent detection".
Let's say you are playing with your friends at the park and someone new comes along. You might look at them and try to figure out if they seem nice or not. You might listen to their voice, watch how they behave, and see how they treat others. This is you using your agent detection skills, trying to figure out if they are a friend or a potential threat.
Animals do this too! Some animals are great at figuring out who is part of their group, who is a stranger, and who might be a predator. For example, meerkats live in a big family and they are always careful about who they let near them. They have to be cautious because some animals might try to kill and eat them! So, they use their agent detection skills to keep their family safe.
So, agent detection is when animals or humans try to figure out if someone or something is a friend or a threat. Just like a spy!