A computational instance may contain queues configured to hold work items. The work items may be representations of user submissions requesting actions from a plurality of agents. The computational instance may also contain computing devices configured to: (a) obtain a set of assignment rules that specify mappings between (i) respective selection criteria for the assignment rules, and (ii) one or more candidate agents from the plurality of agents that can be assigned to address the work items with content that match the respective selection criteria, (b) read, from the queues, a work item corresponding to a user submission, (c) iterate through the assignment rules according to an ordering until a particular assignment rule with associated selection criteria that matches content of the work item is found, and (d) assign the work item to a particular agent from the one or more candidate agents.