Chrome Inspect A11Y

chrome-inspect-a11y

DOM snapshot + targeted evaluation to produce a focused accessibility report for a page or element. Use for live runtime a11y checks (for static source-code review, use audit-a11y-code).

Requires: Chrome DevTools MCP server running and connected.

Inputs

If filePath is omitted, auto-name: ./tmp/a11y-<sanitized-scope>.png

sanitize(x): lowercase; keep a–z 0–9 - _; replace other chars with -.

Procedure

1. Snapshot

mcp__chrome__take_snapshot: { "includeAccessibility": true, "includeAttributes": true, "includeFrames": true }

2. Resolve target

• If ${input:scope} is a selector: find uid for the element.
• If page: work at the document root.

3. Collect a11y data via mcp__chrome__evaluate_script

Role, name, relationships:

(() => {
  const el = /* resolved element or document.body */;
  return {
    role: el.getAttribute('role') || el.tagName.toLowerCase(),
    ariaLabel: el.getAttribute('aria-label'),
    labelledby: el.getAttribute('aria-labelledby'),
    describedby: el.getAttribute('aria-describedby'),
    ariaModal: el.getAttribute('aria-modal'),
    ariaRequired: el.getAttribute('aria-required'),
    ariaExpanded: el.getAttribute('aria-expanded'),
    ariaDisabled: el.getAttribute('aria-disabled'),
    tabIndex: el.tabIndex,
    focusable: el.matches('a,button,input,select,textarea,[tabindex]'),
  };
})()

Contrast check (text elements):

(() => {
  const s = getComputedStyle(element);
  return { color: s.color, background: s.backgroundColor, fontSize: s.fontSize };
})()

Flag if color vs background contrast appears below 4.5:1 (WCAG AA for normal text) or 3:1 (large text ≥18pt / 14pt bold). This is a best-effort approximation from computed values.

Dialog/modal check (when scope is a dialog):

(() => ({
  role: element.getAttribute('role'),
  ariaModal: element.getAttribute('aria-modal'),
  labelledby: element.getAttribute('aria-labelledby'),
  labelText: document.getElementById(element.getAttribute('aria-labelledby'))?.textContent?.trim(),
}))()

4. Keyboard checks (static inference)

• Is the element naturally focusable? (a, button, input, select, textarea)
• If not, does it have tabindex="0"?
• Does it have tabindex="-1" (programmatically focusable only)?
• Note any missing keyboard attributes.

5. Screenshot to filePath

Resolve to absolute path, create parent dirs, call mcp__chrome__take_screenshot.

Output Format

♿ Accessibility Summary

• Scope: ${input:scope}
• role / name / labelledby / describedby / aria-modal / focusable / tabIndex

⚠️ Issues

Bullet list — missing label, dialog lacks aria-modal, insufficient contrast, non-focusable interactive element, etc. Include WCAG criterion reference where applicable (e.g., WCAG 2.1 SC 1.4.3, 4.1.2).

✅ Passes

Elements/attributes that are correctly implemented.

🖼 Screenshot

Saved: <absolute path>

WCAG Quick Reference

Common Mistakes

• Not using includeFrames: true — misses elements in iframes (Storybook, embedded widgets).
• Checking wrapper instead of native control — role/tabIndex on the wrapper may differ from the inner <input>.
• Contrast approximation only — computed color values may not account for opacity layering; use a dedicated contrast tool for final verification.