A system to determine operational statuses of agents interfacing with digital assistant applications, comprising: a response logger component executed by a data processing system having one or more processors to access a log database, the log database maintaining a plurality of response metrics for each of a plurality of agent services, each response metric corresponding to a response by a respective agent service to a respective first request generated by a digital assistant application responsive to a input audio signal for one of the plurality of functions of an agent interfacing with the digital assistant application, wherein the digital assistant application is a digital assistant application of the data processing system; a probe monitor component executed by the data processing system and configured to transmit a respective second request to each of the agent services for one of the plurality of functions of the associated agent and to wait for a respective second response from the agent service in response to the second request; a status evaluator component executed by the data processing system and configured to determine an operational status of each of the agent services for the agents based on the plurality of response metrics maintained on the log database for the agents and on a time elapsed since the transmission of the respective second request; and an agent manager component executed by the data processing system and configured to cause the digital assistant application to perform an action in interfacing with an agent based on the operational status of the associated agent service, wherein the response logger component or the probe monitor component is configured to use the responses from the agents to determine one or more functions for each of the agents; wherein the response logger component or the probe monitor component is configured to identify an alternative agent to be substitutable with an agent based on the one or more functions determined for the agent and the one or more functions determined for the alternative agent, and wherein the agent manager component is configured, based on identifying the operational status of an agent service as unresponsive, to cause the digital assistant application to perform the action of selecting, responsive to a second input audio signal for one of the plurality of functions of the associated agent, the identified alternative agent. a response logger component executed by a data processing system having one or more processors to access a log database, the log database maintaining a plurality of response metrics for each of a plurality of agent services, each response metric corresponding to a response by a respective agent service to a respective first request generated by a digital assistant application responsive to a input audio signal for one of the plurality of functions of an agent interfacing with the digital assistant application, wherein the digital assistant application is a digital assistant application of the data processing system; a probe monitor component executed by the data processing system and configured to transmit a respective second request to each of the agent services for one of the plurality of functions of the associated agent and to wait for a respective second response from the agent service in response to the second request; a status evaluator component executed by the data processing system and configured to determine an operational status of each of the agent services for the agents based on the plurality of response metrics maintained on the log database for the agents and on a time elapsed since the transmission of the respective second request; and an agent manager component executed by the data processing system and configured to cause the digital assistant application to perform an action in interfacing with an agent based on the operational status of the associated agent service, wherein the response logger component or the probe monitor component is configured to use the responses from the agents to determine one or more functions for each of the agents; wherein the response logger component or the probe monitor component is configured to identify an alternative agent to be substitutable with an agent based on the one or more functions determined for the agent and the one or more functions determined for the alternative agent, and wherein the agent manager component is configured, based on identifying the operational status of an agent service as unresponsive, to cause the digital assistant application to perform the action of selecting, responsive to a second input audio signal for one of the plurality of functions of the associated agent, the identified alternative agent.