The Meta-Documentation Dilemma
In his terrific “Effective architecture sketches” slide deck, Simon Brown rightly states that you don’t need UML to sketch up your software architecture. However, if you don’t, you need to consider documenting the documentation:
The utility of using a standard like UML is that you don’t have to spend any time on all the arcane subtleties of meta-documentation. And if you’re choosing to bypass the UML, you’re probably not going to spend much time, if any, doing meta-documentation to clarify your architecture decisions. After all, doing less documentation, let alone writing documentation about the documentation, is why you eschewed UML in the first place.
So, good luck in unambiguously communicating the software architecture to your stakeholders; especially those poor souls who will be trying to build the beast with you.