Mastering Design System Documentation

01What to Document

Every component needs four types of documentation: usage guidelines (when to use this component and when not to), API reference (props, variants, sizes, states), accessibility notes (keyboard behavior, ARIA attributes, screen reader announcements), and examples (common patterns, edge cases, do's and don'ts).

Usage guidelines are the most important and the most often skipped. Engineers can figure out the API from TypeScript types. But knowing when to use a Dialog vs. a Drawer vs. a Popover requires context that types cannot express. Usage guidelines capture the design intent — the why behind the component.

At TCTF, every component page starts with a one-sentence description, followed by a 'When to use' section and a 'When not to use' section. These sections prevent the most common misuse patterns.

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Usage guidelines > API reference. Engineers can read types. They cannot read design intent. Document the why, not just the what.

02Structure for Discoverability

Documentation that cannot be found is documentation that does not exist. Structure determines discoverability.

We organize our design system documentation in three layers: foundations (color, typography, spacing, elevation, motion), components (buttons, inputs, cards, modals, tables), and patterns (forms, navigation, data display, feedback, layouts).

Foundations are the building blocks that components use. Components are the reusable UI elements. Patterns are the compositions of components that solve common UX problems. This hierarchy mirrors how designers and engineers think about building interfaces — from abstract to concrete.

Every page has a consistent structure: overview, usage guidelines, API reference, accessibility, examples, and related components. Consistency in structure means users learn the documentation format once and can navigate any component page efficiently.

03Keeping Documentation Current

Stale documentation is worse than no documentation — it creates false confidence. The component behaves differently than documented, the engineer builds based on the docs, and the result is a bug that is hard to trace.

We keep documentation current with three practices: documentation is part of the PR (every component change must include a documentation update), automated visual regression tests catch undocumented visual changes, and quarterly documentation audits review every page for accuracy.

The PR requirement is the most effective. When documentation is a merge requirement, it gets updated. When it is optional, it does not. Our CI pipeline checks that every component file change includes a corresponding documentation file change. If it does not, the PR cannot merge.

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Documentation is a merge requirement. No doc update = no merge. This single rule keeps 80+ component pages current.

04Accessibility Documentation

Accessibility documentation is not optional — it is the most important section of every component page. If a component is not accessible, it should not ship.

Every component page includes: keyboard interaction (which keys do what), ARIA attributes (roles, states, properties), screen reader behavior (what is announced and when), focus management (where focus moves on open, close, and navigation), and color contrast (minimum ratios for all variants).

We also include a 'Testing' section that describes how to verify accessibility: which automated tools to run (axe, Lighthouse), which manual tests to perform (keyboard navigation, screen reader walkthrough), and which edge cases to check (high contrast mode, reduced motion, zoom levels).