Systems and methods for auditing an operation of an ambulatory medical device (AMD) are described. A system may include an auditor device and an analyzer circuit communicatively coupled to each other. The auditor device can sense from the patient, independently of and during the operation of the AMD, information about the operation of the AMD including sensed electrostimulation and a physiological signal in response to the electrostimulation. The analyzer unit may generate a device audit indicator indicating the functionality and performance of the AMD using the sensed physiological signal and the sensed AMD operation information. The system may output the device audit indicator to a user or a process, or to program device therapy for the AMD based on the device audit indicator.