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

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:

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

Dependencies

• @modelcontextprotocol/sdk - MCP server framework

• axe-core - Deque accessibility testing engine

• accessibility-checker - IBM Equal Access engine

• playwright - Headless browser automation

License

MIT