Annotate anything with a business, logical, or technical constraint

Constraints shape design decisions but often remain invisible in wireframes. Password requirements, character limits, regulatory compliance, API limitations, and business rules all affect user experience. Without annotations explaining these constraints, teams waste time questioning or incorrectly implementing features.

Document not just what constraints exist, but why they matter. "Username: 3-20 characters (database limitation)" provides context. "Price updates every 15 minutes (exchange API refresh rate)" explains seemingly arbitrary behavior. This transparency helps teams work within limitations rather than against them.

Include business logic that affects user experience: calculation formulas, approval workflows, inventory rules, or pricing tiers. These annotations transform wireframes from interface drawings into system specifications that account for real-world complexity.^[1]