Harvey A. Ramer

Documentation is central to the user experience of your API. It is not an add-on. Invest in high-quality documentation; you will see higher returns than investing in more features.

…ral any feedback provided to a user in the course of interacting with your API, is part of the API. Interactivity and feedback are integral to the user experience. Design your API’s error messages deliberately.

…n argument should be understandable without having any context about the underlying implementation. Arguments that have to be specified by users should relate to the mental models that the users have about the problem, not to implementation details in your code. An API is all about the problem it solves, not about how the software works in the background.