Modularity asks whether the product is composed of parts with clear boundaries. A measure relates the coupling or cohesion observed to the structure intended. Modularity is structural and can be measured from code and dependency data. The useful measures are about boundaries: dependencies across a boundary, cycles, the size of the public surface, the number of modules that must change together. A high module count is not modularity. The measure should be tied to the intended architecture, because a product can be modular in a way nobody planned and still be hard to change.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.