Accessibility Testing MCP

An MCP server for accessibility testing using axe-core and IBM Equal Access. Choose your testing engine or use both for comprehensive coverage.

Example Prompts

• "Test the accessibility of https://example.com"
• "Test the accessibility of https://example.com" blockers only output issues in chat: What is the Issue, Who it Impacts, How to Fix, WCAG, Severity, Code Snippet"

Dual Engine Support

• Axe-core (Deque) - Industry standard, zero false positives
• IBM Equal Access - Comprehensive IBM accessibility requirements

Multi-Screen Testing

Test at multiple viewport sizes to catch responsive accessibility issues.

Tools

Tool	Description
analyze_url	Test any URL for accessibility issues
analyze_url_json	URL test with raw JSON output
analyze_html	Test HTML content directly
analyze_html_json	HTML test with raw JSON output
get_rules	List available accessibility rules

All tools accept an optional engine parameter ("axe" or "ace").

Installation

npm install
npm run build

Configuration

Environment Variables

Configure via MCP config env section:

Variable	Values	Default	Description
A11Y_ENGINE	axe, ace	axe	Testing engine
WCAG_LEVEL	2.0_A, 2.0_AA, 2.1_A, 2.1_AA, 2.2_AA, etc.	2.1_AA	WCAG version & level
BEST_PRACTICES	true, false	true	Include best practices/recommendations
SCREEN_SIZES	Comma-separated WIDTHxHEIGHT	1280x1024	Viewport sizes to test
HEADLESS_BROWSER	true, false	true	Run browser in headless mode; set to false to open visible browser

The WCAG_LEVEL setting automatically configures both Axe-core tags and IBM Equal Access policies.

VS Code (GitHub Copilot)

Add to VS Code settings (JSON):

"mcp": {
  "servers": {
    "accessibility-testing-mcp": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/accessibility-testing-mcp/build/index.js"],
      "env": {
        "A11Y_ENGINE": "axe",
        "WCAG_LEVEL": "2.2_AA",
        "BEST_PRACTICES": "true",
        "SCREEN_SIZES": "1280x1024,320x640",
        "HEADLESS_BROWSER": "true"
      }
    }
  }
}

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "accessibility": {
      "command": "node",
      "args": ["/path/to/accessibility-testing-mcp/build/index.js"],
      "env": {
        "A11Y_ENGINE": "ace",
        "WCAG_LEVEL": "2.2_AA",
        "BEST_PRACTICES": "true"
      }
    }
  }
}

Understanding Results

Axe-core Output

• Violations: Definite accessibility failures
• Incomplete: Needs manual review
• Passes: Rules that passed
• Inapplicable: Rules that don't apply

IBM Equal Access Output

• Violations: Accessibility failures
• Potential Violations: Needs review
• Recommendations: Suggested improvements (when BEST_PRACTICES=true)
• Manual Checks: Requires human testing

WCAG_LEVEL Values

Level	Description
2.0_A	WCAG 2.0 Level A
2.0_AA	WCAG 2.0 Level AA
2.1_A	WCAG 2.1 Level A
2.1_AA	WCAG 2.1 Level AA (default)
2.1_AAA	WCAG 2.1 Level AAA
2.2_A	WCAG 2.2 Level A
2.2_AA	WCAG 2.2 Level AA
2.2_AAA	WCAG 2.2 Level AAA

Dependencies

• @modelcontextprotocol/sdk - MCP server framework
• axe-core - Deque accessibility testing engine
• accessibility-checker - IBM Equal Access engine
• playwright - Headless browser automation

License

MIT