Conditions are leaf nodes that check some form of state in the game. For example if the agent have a certain weapon or if there is a target in range. In the end they return a boolean value in the form of success or failure. There are two main modes of operation for conditions.
Instant: Check if the condition is true at this point in time and return the result immediately as success or failure.
Monitoring: Keep return running for as long as the condition is true and then return failure when it is false.