The on/off $AgentPriorty status of an agent's query is shown in its view icon, for all views except Maps.
Disabled (frozen) agents are distinguished by a hollow bar (the screen grab's compression makes it less clear than it actually is on screen!). Note that a frozen agent retains any existing aliases as the time of being disabled, those these may subsequently be deleted if so desired.
Outline, Chart and Attribute Browser are the only views to offer this visual tell-back of $AgentPriority status.