In one embodiment, a method includes receiving a user request associated with one or more domains from a client system associated with a first user, parsing the user request to identify one or more semantic-intents are associated with the one or more domains and one or more slots, identifying, based on a ranker model, one or more dialog-intents associated with the user request based on the one or more semantic-intents and slots and context information associated with the user request, wherein each dialog-intent is a sub-intent of one or more of the semantic-intents, determining one or more agents for executing one or more tasks associated with the one or more dialog-intents respectively, and sending instructions for presenting a communication content information returned from the one or more agents responsive to executing the one or more tasks responsive to the user input to the client system.