accessibility-mcp-server

MCP-Server for Web Accessibility Checks (WCAG 2.1/2.2)

Gives AI agents the ability to check websites for accessibility issues, validate ARIA attributes, check color contrast ratios, and generate full accessibility reports — without any API key.

Features

• WCAG 2.1 AA Compliance Checks — Automated checks for 10+ WCAG success criteria

• Color Contrast Analyzer — Calculates contrast ratios and WCAG AA/AAA pass/fail

• ARIA Validator — Checks ARIA roles and attributes for correctness

• Heading Structure Analyzer — Validates heading hierarchy (H1→H2→H3...)

• Image Alt Text Checker — Finds images missing alt attributes

• Form Label Validator — Ensures all form inputs have accessible labels

• Full A11y Report — Comprehensive report with accessibility score (0-100)

• WCAG Rule Reference — Browse all WCAG 2.1 A/AA/AAA rules

• No API Key Required — Works with any public website

Related MCP server: aria51 MCP Server

Tools

Installation

pip install accessibility-mcp-server

Usage with Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "accessibility": {
      "command": "accessibility-mcp-server"
    }
  }
}

Example Prompts

• "Check https://example.com for accessibility issues"

• "What is the contrast ratio between #333333 and #ffffff?"

• "Generate a full accessibility report for https://mysite.com"

• "Check if the images on https://example.com have alt text"

• "Validate the ARIA in this HTML: <div role='buttn'>Click</div>"

• "List all WCAG 2.1 AA rules"

WCAG Criteria Checked

Tech Stack

• Python 3.10+ with FastMCP

• httpx for async HTTP requests

• BeautifulSoup4 + lxml for HTML parsing

• WCAG formulas implemented directly (relative luminance, contrast ratio)

License

MIT — Free for personal and commercial use.

Built by AiAgentKarl | Part of the AI Agent Tools ecosystem