A11y MCP Server

An MCP (Model Context Protocol) server for performing accessibility audits on webpages using axe-core. Use the results in an agentic loop with your favorite AI assistants (Cline/Cursor/GH Copilot) and let them fix a11y issues for you!

Features

• Perform detailed accessibility audits on any webpage
• Get a summary of accessibility issues
• Filter audits by specific WCAG criteria
• Include HTML snippets in the results for easier debugging

Installation

# Install globally
npm install -g a11y-mcp

# Or use directly with npx
npx a11y-mcp

Configuration

To use this MCP server with Cline, you need to add it to your MCP settings configuration file.

MCP configuration

Add the following to the mcpServers object:

{
  "mcpServers": {
    "a11y": {
      "command": "npx",
      "args": ["a11y-mcp"],
      "disabled": false,
      "autoApprove": []
    }
  }
}

Available Tools

audit_webpage

Performs a detailed accessibility audit on a webpage.

Parameters:

• url (required): URL of the webpage to audit
• includeHtml (optional): Whether to include HTML snippets in the results (default: false)
• tags (optional): Array of specific accessibility tags to check (e.g., wcag2a, wcag2aa, wcag21a, best-practice)

Example:

Use the a11y MCP server to audit example.com for accessibility issues

get_summary

Gets a summary of accessibility issues for a webpage.

Parameters:

• url (required): URL of the webpage to audit

Example:

Give me an accessibility summary of example.com

Example Usage

Once configured, you can ask Claude to use the MCP server to perform accessibility audits:

1. "Can you check example.com for accessibility issues?"
2. "Audit my website at https://mywebsite.com for WCAG 2.1 AA compliance"
3. "Give me a summary of accessibility issues on https://example.com"
4. "Check if my local development server at http://localhost:3000 has any critical accessibility problems"

Development

To run the server locally for development:

npm start

Releasing

This project includes a release script to help with versioning and publishing to npm. The script handles version bumping, running tests, git tagging, and npm publishing.

To release a new version:

# Make sure the script is executable
chmod +x release.sh

# Release a patch version (default)
./release.sh

# Release a minor version
./release.sh --minor

# Release a major version
./release.sh --major

# Release a specific version
./release.sh --version=1.2.3

# Skip git operations
./release.sh --skip-git

# Dry run (no changes will be made)
./release.sh --dry-run

# Force release even with uncommitted changes
./release.sh --force

For more information, run:

./release.sh --help

License

MPL 2.0

Credits

This project builds atop the awesome work done by axe-core

Security and hosting

Requires Node.js 22.12 or newer. Chrome runs with its sandbox enabled. Every HTTP(S) connection, including redirects and subresources, goes through a validating proxy that pins the destination IP. Private, link-local, multicast, reserved, and cloud metadata addresses are blocked, including mapped IPv6. Loopback remains available for local development; set AUDIT_ALLOW_LOOPBACK=false for public-only audits. LAN addresses are no longer supported. One audit runs per MCP process, with a 90-second browser deadline. For hosted use, additionally isolate browser workers and enforce network egress restrictions at the infrastructure layer. Automated axe checks do not establish WCAG conformance; manual review is still required.

Run npm test, npm run test:smoke (requires Chrome), and npm audit.