A quality requirement describes a constraint or performance target that functional statements do not cover. For example, it can address performance, availability, maintainability, security, reliability, and usability. Functional requirements describe what the system does. By contrast, this type of statement describes how well the system must do it. For example, “The system must be easy to handle” expresses a usability expectation. On the other hand, “The user can start the video from the training overview with one click” describes a concrete function.
Acceptance criteria make these expectations testable. They define the conditions a statement must meet to gain stakeholder acceptance. Therefore, I attach acceptance criteria to both functional items and these cross-cutting constraints. For example, for “Only direct managers may see personnel records,” I add checks such as logging all access and proving that a non-manager cannot view those records. In addition, a certification against a security standard may be necessary. Thus, measurable checks turn abstract expectations into verifiable outcomes.
Agile teams can document these expectations in several ways. If the constraint affects only one backlog item, I attach it directly to that item. However, when it affects many items, I capture it outside the backlog, for example as separate cards or in a tree that breaks it down. Next, I link it to all relevant functional items using tool links or simple identifiers. In addition, I reflect it in the team’s Definition of Done so the team applies the right checks consistently.
Vague statements need sharpening. First, I decompose a broad phrase into finer-grained, testable parts. For example, I split “user friendly” into “easy to learn” and “easy to handle.” Second, I derive functional features when the constraint implies concrete behavior. For instance, secure access often leads to role-based access control as a functional capability.
Teams should treat the Definition of Done as context-specific, not reusable by copy-paste. Therefore, I review which parts apply and which do not. Moreover, I write clear acceptance criteria for each cross-cutting constraint so testers and stakeholders can verify compliance. Finally, I practice deliberately: I pick two such constraints and draft acceptance criteria for each. This exercise strengthens clarity, validation, and implementation decisions.
In short, I treat these statements as system-wide expectations about how the solution performs and what limits it must respect. Then I make them precise, connect them to functional work, and define acceptance checks. As a result, clarity, testability, and stakeholder alignment improve.