usage of packages and tool classes

[csquaredphd]

I'm looking for clarification on the intended usage of the multiple packages (edalize, edalize.tools, edalize.flows). I have searched the code, issues, and Wiki and understand that edalize.flows is the newest API (which I think is a good move, BTW). The distinction is less clear between edalize and edalize.tools.

For example, if one wanted to add new tool options to Vivado and Yosys, to which package(s) should they be added?

Which package should a newly developed project that incorporates edalize use?