I am working as a software engineer turned team leader in a large software company. One of my areas of strength is node.js, and we are in the process of moving a lot of our services to separate node.js services, which is proving to be very successful so far.
However, I am supposed to stop day to day development of small node.js services, and simply lay down a proper specification, so that one of my team members can work on the actual code.
I am aware of tools like UML, but I don't think they apply to a system with apis built with node.js/express. I have made a few flowcharts, but my seniors want me to be very complete with the spec, down to each implementation detail.