We propose an axiomatic framework to account for observer-dependent describability inmodern physics. While existing theories precisely describe differences in observational outcomes,they do not explicitly formalize why the same physical system must be described by structurallydifferent models depending on the observer. We introduce the notion of topological degrees offreedom as a meta-level condition that constrains describability itself. This axiom does notreplace existing physical theories but reorganizes their domains of applicability.