WCAG Accessibility MCP

A WCAG accessibility testing MCP for AI agents, Codex, Claude Code, and automated UI audits.

WCAG Accessibility MCP gives AI coding and design agents a real accessibility feedback loop. It renders web interfaces in Chromium, runs axe-core, checks color contrast, maps findings to WCAG guidance, and returns structured evidence that an agent can use to fix accessibility issues before a UI is treated as complete.

It is designed for people building with AI: product designers, design engineers, frontend developers, AI product teams, and anyone using agents to generate or review web interfaces.

This is an automated testing aid, not a WCAG certification service. It catches many common failures, but full accessibility review still requires human testing for keyboard behavior, focus order, screen readers, zoom, motion, content quality, and assistive-technology behavior.

Why This Exists

AI-generated interfaces often look polished but fail basic accessibility checks: weak contrast, missing labels, broken semantic structure, poor ARIA usage, inaccessible forms, and hidden keyboard issues.

This MCP helps agents stop guessing. Instead of saying “follow WCAG,” it gives them testable feedback:

• what failed
• where it failed
• which element was affected
• which WCAG-related rule applies
• what needs to be fixed
• which checks still require manual review

What It Can Do

Standards Coverage

The server supports these profiles:

• wcag2a
• wcag2aa
• wcag2aaa
• wcag21aa
• wcag21aaa
• wcag22aa
• wcag22aaa
• best-practice

AA profiles include Level A and AA criteria. AAA profiles include Level A, AA, and AAA criteria.

The default profile is wcag22aa.

For WCAG 2.2:

• AA includes 55 required success criteria.
• AAA includes 86 required success criteria.

An automated axe mapping means partial automated coverage. It does not mean the whole WCAG success criterion has been fully tested.

Install

Requirements:

• Node.js 20 or newer
• Chrome or Edge recommended
• Windows, macOS, or Linux

Install from npm:

npm install -g wcag-accessibility-mcp

Or run directly:

npx -y wcag-accessibility-mcp

If the server starts correctly, you should see:

a11y-feedback-mcp is running over stdio

The startup message may still use the internal legacy name, but the published package and registry name are wcag-accessibility-mcp.

Use With Claude Code

Add the MCP server:

claude mcp add --scope user wcag-accessibility -- npx -y wcag-accessibility-mcp

Check that it is connected:

claude mcp list

Test prompt:

Use the wcag-accessibility MCP tool check_contrast. Check #999999 on #ffffff for WCAG AA normal text. Do not calculate manually.

Expected result:

The contrast ratio is about 2.85:1, which fails WCAG AA for normal text.

Use With Claude Desktop

Open the Claude desktop config file on Windows:

notepad "$env:APPDATA\Claude\claude_desktop_config.json"

Add this inside mcpServers:

{
  "mcpServers": {
    "wcag-accessibility": {
      "command": "C:\\Program Files\\nodejs\\npx.cmd",
      "args": [
        "-y",
        "wcag-accessibility-mcp"
      ]
    }
  }
}

If you already have another MCP server, keep it and add wcag-accessibility as a second entry.

Then fully quit Claude Desktop and reopen it.

Use With Codex

Add the MCP serv

... View full README on GitHub