Summary: This work is focused on understanding the impact of uncertainties on various input parameters on the lift production for a flapping-wing drone equipped with a vibratory-based actuation mechanism. Uncertainty and sensitivity analysis techniques are used to investigate output trends under various input distribution types and ranges to determine the critical parameters that should be considered during the design phase. Two cases are investigated in this work: The first considers a purely linear actuation mechanism, and the second includes a cubic nonlinear spring. Input parameters under consideration are prescribed with varying levels of uncertainties and distributions. Results show that as input uncertainty increases, the range of outputs quickly increases and that there is a high chance of optimal performance failure from the drone. In addition, it is shown that input forcing and excitation frequency are the most influential parameters when operating at resonance and that the excitation frequency alone is the dominant parameter in the off-resonance regime. Lastly, uncertainty in the nonlinear stiffness results in the possibility of the drone producing low lift. These results can be used by researchers and designers to properly design vibratory-based actuation mechanisms for flapping-wing drones by considering the more influential parameters and ensuring they are designed with optimal performance.