design-md-validator

name	design-md-validator
description	Validate DESIGN.md files against the official Google specification using the `@google/design.md` CLI linter. Works with local files and remote URLs. Use when the user wants to lint a DESIGN.md, check spec compliance, find broken token references, verify WCAG contrast ratios, diff two versions, export tokens to Tailwind or DTCG format, or audit a design system file for structural correctness. Trigger on mentions of "validate DESIGN.md", "lint DESIGN.md", "check my design.md", "design.md spec compliance", "WCAG contrast check", "broken token references", "design token validation", "export design tokens", "diff design systems", "design.md audit", "@google/design.md", "npx design.md lint", "design system validation", "frontmatter tokens", or any request to verify a DESIGN.md file.
metadata	{"author":"https://ft.ia.br","version":"1.1","date":"2026-07-18T00:00:00.000Z","repository":"https://github.com/fabricioctelles/skills","license":"Apache 2.0","category":"product-verification","upstream":{"spec":"https://github.com/google-labs-code/design.md","cli":"https://www.npmjs.com/package/@google/design.md","stitch-skills":"https://github.com/google-labs-code/stitch-skills"}}

design-md-validator

Validate, lint, diff, and export DESIGN.md files using the official Google @google/design.md CLI. Always uses the latest published version from npm — no vendored copy, always up-to-date with the spec.

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When to Use

Trigger	Action
User has a DESIGN.md file and wants validation	lint
User wants to compare two versions	diff
User wants to export tokens to Tailwind/DTCG	export
User wants to see the current spec	spec
User shares a URL to a raw DESIGN.md	Fetch → lint
User asks "is my design.md valid?"	lint + interpret findings

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Core Commands

All commands use npx @google/design.md to ensure the latest version is always used. Never install globally — npx resolves from the public npm registry.

Lint (validate)

npx @google/design.md lint DESIGN.md

Output: JSON with findings[] and summary { errors, warnings, infos }. Exit code 1 if errors found, 0 otherwise.

Diff (compare versions)

npx @google/design.md diff DESIGN.md DESIGN-v2.md

Output: JSON with token-level changes (added, removed, modified) and regression flag. Exit codes: 0 no regression, 1 regression (errors in "after" > errors in "before"), 2 input failure (file not found or unreadable).

Export (to other formats)

# Tailwind v3 config
npx @google/design.md export --format json-tailwind DESIGN.md

# Tailwind v4 CSS theme
npx @google/design.md export --format css-tailwind DESIGN.md

# W3C Design Tokens (DTCG)
npx @google/design.md export --format dtcg DESIGN.md

# CSS custom properties (optional --prefix)
npx @google/design.md export --format css-vars DESIGN.md
npx @google/design.md export --format css-vars --prefix ds DESIGN.md

css-vars is available on main, ships in the next release — if the CLI rejects the format, npm is still on 0.3.0.

Spec (output the format specification)

npx @google/design.md spec
npx @google/design.md spec --rules
npx @google/design.md spec --rules-only --format json

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Workflow

1. Obtain the DESIGN.md

Local file:

npx @google/design.md lint ./DESIGN.md

From URL (fetch first):

curl -sL <url> > /tmp/DESIGN.md && npx @google/design.md lint /tmp/DESIGN.md

From stdin:

cat DESIGN.md | npx @google/design.md lint -

2. Discover the Active Rule Set

Before interpreting anything, check which rules the installed CLI actually runs — the rule set changes between releases, and the bundled references are a fallback, not the authoritative source:

npx @google/design.md spec --rules-only --format json

3. Run Lint

npx @google/design.md lint --format json DESIGN.md

4. Interpret Findings

Parse the JSON output and report to the user:

Severity	Meaning	Action
error	Spec violation — file is invalid	Must fix
warning	Best practice violation — file is valid but suboptimal	Should fix
info	Informational — suggestions for improvement	Nice to fix

5. Provide Actionable Fixes

For each finding, explain:

1. What the rule checks
2. Why it matters
3. How to fix it with a concrete code example

6. Re-validate After Fixes

After applying fixes, re-run lint to confirm the file passes.

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Linting Rules Reference

Load references/linting-rules.md for the complete rule table when providing detailed explanations of lint failures.

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Token Schema Quick Reference

Load references/token-schema.md for the complete YAML frontmatter schema when helping users author or fix their frontmatter tokens.

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Windows Compatibility

On Windows/PowerShell, the .md suffix in the bin name collides with Markdown file associations. Use the designmd alias:

npx -p @google/design.md designmd lint DESIGN.md

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Related Official Skills

Skill	Source	Purpose
stitch-design-taste	google-labs-code/stitch-skills	Generates DESIGN.md for Google Stitch
design-md (Stitch plugin)	google-labs-code/stitch-skills	Analyzes Stitch projects → DESIGN.md
taste-design (MCP)	mcpservers.org	MCP server for Stitch design extraction

Install the official Stitch skill for generation:

npx skills add https://github.com/google-labs-code/stitch-skills --skill design-md

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Anti-Patterns

• Never vendor or cache the CLI — always use npx for latest spec
• Never manually parse YAML frontmatter when the linter can do it
• Never guess at contrast ratios — let the linter compute them
• Never assume section order is correct — let the linter verify
• Never skip re-validation after fixes
• Never assume the rule set from memory or from the bundled references — confirm it at runtime with spec --rules-only

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Example Session

User: validate my DESIGN.md

Agent:
1. Reads the file
2. Runs: npx @google/design.md spec --rules-only --format json
3. Runs: npx @google/design.md lint --format json DESIGN.md
4. Parses output
5. Reports:
   - summary: { errors: 0, warnings: 2, infos: 1 }
   - WARNING: contrast-ratio — button textColor on backgroundColor is 3.8:1 (needs 4.5:1)
   - WARNING: orphaned-tokens — color "accent-muted" defined but never used
   - INFO: token-summary — 5 colors, 3 typography, 2 rounded, 2 spacing
6. Suggests fixes with code
7. Re-runs lint to confirm