A note on the monotonicity of observational ergotropic advantage

Very recently, Mahanti et al. (arXiv:2609.18735) introduced the observational ergotropic advantage, which gives the maximum value of extra work that a measurement can obtain with respect to all incoherent measurements. However, the above quantity does not show monotonic behaviour under the resource theory of measurement coherence. So, the search for a resource theory in which it is a monotone was open. We derive the monotonicity of this quantity using energy-preserving channels and passive resets as free operations and energy-incoherent measurements as free objects. We show the monotonicity property of the measure as a necessary criterion of measurement transformation, but it turns out not to be a sufficient condition. It is further established that the measure is not convex. A short analysis of bounds and tightness of the measure using a degenerate Hamiltonian is also given.