wcag-auditor

WCAG Auditor Skill

This skill provides WCAG 2.1 accessibility audit capabilities, including criteria definitions, check implementations, and scoring logic.

Purpose

Systematically evaluate web pages against WCAG 2.1 Level A and AA success criteria to identify accessibility barriers and provide remediation guidance.

WCAG 2.1 Overview

WCAG is organized around four principles (POUR):

• Perceivable: Information must be presentable to users
• Operable: Interface must be usable
• Understandable: Information and operation must be understandable
• Robust: Content must be interpretable by assistive technologies

Conformance Levels

Level	Description	Requirements
A	Minimum	Essential accessibility
AA	Standard	Most common requirement
AAA	Enhanced	Highest accessibility

This skill implements Level A and AA checks.

Check Implementation Guide

Using browser_evaluate for DOM Checks

Most WCAG checks can be performed via JavaScript evaluation:

// Example: Check for images without alt text
(function() {
  const images = document.querySelectorAll('img');
  const violations = [];

  images.forEach(function(img) {
    if (!img.hasAttribute('alt')) {
      violations.push({
        element: img.outerHTML.substring(0, 100),
        selector: getSelector(img)
      });
    }
  });

  return { passed: violations.length === 0, violations: violations };
})();

Using browser_snapshot for Accessibility Tree

The accessibility snapshot provides:

• ARIA roles and properties
• Accessible names
• Focusable elements
• Heading structure

Parse the snapshot to verify semantic structure.

Using browser_press_key for Keyboard Tests

Tab through the page to verify:

• All interactive elements are reachable
• Focus order is logical
• No focus traps exist

Criteria Reference

Level A Criteria

1.1.1 Non-text Content

Requirement: All non-text content has a text alternative.