Lay out the Context An API does not live in isolation. It is part of business, involves people, and may sit next to other APIs. All these are necessary to scope and design the API. Instead of that, you could create many integration pipes. It would be difficult to understand them all in a few years. Input: Interviews, relevant api designs, business & architecture diagrams, engineering docs. Identify the nonfunctional requirements Review the security model & performance expectations.