Use Cases

Use Cases describe the concrete ways an API or product actually gets applied by a specific actor to accomplish a specific goal. Where a feature list says what a system can do, a use case says who does what, in what order, and why. It is one of the oldest and most durable ways we have of connecting technical capabilities to the human and business outcomes they are meant to serve.

• Actor and goal - Every use case starts with someone (a developer, an end user, an agent, another system) trying to accomplish a specific outcome.
• A concrete scenario - The steps, inputs, and expected results that walk from intent to completion, including the edges where things go wrong.
• Business framing - The reason the scenario matters, which is what turns a technical detail into a decision someone will pay for or prioritize.
• Reusability - Well-written use cases become the seeds for documentation, tutorials, tests, and onboarding flows across the API lifecycle.

In real API operations, use cases are how I keep design honest. Cataloging the use cases an API supports turns a raw reference into a story a consumer can follow, and it is the connective tissue between an OpenAPI contract and the user stories that justify each endpoint. In the agentic turn, clearly articulated use cases are increasingly what let an automated consumer decide whether an API fits its task at all, making them a discovery signal as much as a design artifact.