Web Accessibility Testing (A11y MCP)

Web Accessibility Testing (A11y MCP) is an MCP server that provides language models with direct access to web accessibility auditing tools. It connects LLM clients to the Deque Axe-core rule engine using Puppeteer to render web pages and analyze DOM structures against Web Content Accessibility Guidelines (WCAG). Software engineers, QA automation specialists, and accessibility auditors use this server to inspect live URLs or isolated HTML snippets without leaving their development environments. The server enables AI coding assistants to detect accessibility violations, validate ARIA role and attribute usage, evaluate color contrast ratios across various text styles, and check for forced screen orientations. By returning structured violation reports containing rule descriptions, impact levels, failure summaries, and target selectors, the server allows developers to triage and repair compliance issues systematically across desktop and mobile viewports.

Category: Browser & Web Automation

Tags: accessibility, axe-core, puppeteer, testing, wcag

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How to install and configure Web Accessibility Testing (A11y MCP)

1. Ensure Node.js version 18 or later is installed on your system. 2. Open your client configuration file, such as claude_desktop_config.json for Claude Desktop or .cursor/mcp.json for Cursor. 3. Add the server entry under the mcpServers object: json { "mcpServers": { "a11y-accessibility": { "command": "npx", "args": ["-y", "a11y-mcp-server"] } } } 4. Alternatively, if using Claude Code CLI, run claude mcp add a11y-accessibility -- npx -y a11y-mcp-server. 5. Restart your MCP client to load the newly registered tools.

What you can do with Web Accessibility Testing (A11y MCP)

• Testing live web pages at specified viewport resolutions against WCAG 2.0, 2.1, and 2.2 standards. * Scanning isolated HTML snippets or component templates directly inside an AI code editor before committing. * Checking text color contrast ratios against background hex or RGB values for normal and bold fonts. * Validating ARIA roles, states, and attributes in markup to ensure screen reader compatibility. * Detecting unwanted orientation lock configurations defined within viewport meta tags or document headers.

Key facts

• Open Source
• https://github.com/ronantakizawa/a11ymcp
• Browser & Web Automation, Security & Compliance
• accessibility, axe-core, puppeteer, testing, wcag

Part of MCP Servers

What can Web Accessibility Testing (A11y MCP) do?

Web Accessibility Testing allows AI models to run accessibility audits using Axe-core and Puppeteer. It can scan public URLs or raw HTML strings across custom viewports, inspect ARIA attributes, calculate color contrast ratios against WCAG thresholds, detect orientation locks, and list available accessibility rules.

How do I install Web Accessibility Testing (A11y MCP)?

You can install it by configuring an MCP client such as Claude Desktop or Cursor to execute npx with the arguments -y and a11y-mcp-server. For Claude Code CLI, execute claude mcp add a11y-accessibility -- npx -y a11y-mcp-server and restart your session.

Which MCP clients work with Web Accessibility Testing (A11y MCP)?

The server works with any MCP-compatible environment that supports standard stdio servers. Tested clients include Claude Desktop, Claude Code CLI, Cursor, Windsurf, and Visual Studio Code with Copilot.

Is Web Accessibility Testing (A11y MCP) open source?

Yes, Web Accessibility Testing is an open source project released under the MIT license. You can inspect its source code and contribute via its public GitHub repository.

Which WCAG standards does the server support?

The server supports filtering tests by various accessibility tags including WCAG 2.0 Level A, AA, and AAA, WCAG 2.1 Level A and AA, WCAG 2.2 Level AA, as well as general accessibility best practice rules.