Is any tool around, that can tell how good division of code into modules in my workspace?
It should calculate number of usage of functions/types/... from other module,
vs from current module inside one crate. And the same thing on the crate level in workspace.
Is any such tools around?
This may not directly answer your question, but at least with respect to crate dependencies you can use cargo-tree to visualize the relationship between your crate and its dependencies. As for the individual function/methods/module/struct/enum usages, that is much a harder problem, but one you could solve using syn if you feel adequately motivated.