know if .lib is static or import
Use the lib command. If it's static, lib will show you a pile of .obj files inside. Not so if it's am implib.
lib /list foo.lib
will do it.
Also see:
https://docs.microsoft.com/en-us/cpp/build/reference/managing-a-library
Look in its accompanying header files ,if the function are 'decorated' with __declspec(dllimport) that it's an import library. Or look for an accompanying .def file ,that also tells you that it's an import library.