Ask HN: Designing a Modern API

I'm starting new work in a few weeks where my job will be to design an API and functionality for "cobots" (https://en.wikipedia.org/wiki/Cobot). C++ mostly.

I've designed API's in the past, but it's been a while. I want to design an API that is uniform throughout, clean, and really lets the developers using it to understand exactly what the API does and doesn't do.

Examples, references, reading appreciated.