In one embodiment, a labeling service receives traffic feature data for a cluster of endpoint devices in a network. A device classification service forms the cluster of endpoint devices by applying machine learning-based clustering to the feature data. The labeling service selects a subset of the endpoint devices in the cluster, in an effort to maximize diversity of the traffic feature data of the selected endpoint devices. The labeling service sends a control command into the network, to trigger a traffic behavior by the selected subset. The labeling service receives updated traffic feature data for the selected subset associated with the triggered traffic behavior. The labeling service controls whether a label request is sent to a user interface for labeling of the cluster of endpoint devices with a device type, based on the updated traffic feature data for the subset of endpoint devices in the cluster.