accessibility-testing-mcp by joe-watkins - MCP Server

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

joe-watkins/accessibility-testing-mcp