Aether WCAG Scanner MCP server

Aether WCAG Scanner

A Claude Code plugin that finds WCAG 2.1 AA accessibility violations and returns ready-to-apply fixes — not just a list of problems.

It drives a real browser (Playwright + axe-core) across desktop, tablet, and mobile viewports, then pairs each violation with a concrete fix: corrected HTML, the relevant WCAG success criteria, and technique code examples.

Why it's different

Plain Claude Code can guess at accessibility issues by reading your markup. This plugin actually runs your page and grounds every fix in the WCAG spec.

The scanner degrades gracefully: with no API key (or when offline or rate-limited) it still returns template-based fixes for every violation. Add an API key and the same violations come back with corpus-grounded fixes and WCAG technique snippets.

Install

/plugin marketplace add https://github.com/allchemylabs/claude-plugins.git
/plugin install aether-wcag-scanner@allchemylabs

Once the official Claude Code marketplace listing is live, you can also install it directly from there.

The install prompts for your Allchemy Labs API key; paste the key you got from beta.allchemylabs.ai. To set or change it later:

/plugin configure aether-wcag-scanner@allchemylabs

The first start installs the plugin's dependencies (about a minute) and the first scan downloads Chromium for Playwright. If /mcp shows the server as not connected right after install, wait a moment and run /reload-plugins.

Running without a key

The scanner itself runs locally and works without a key: you get template fixes for every violation. The key adds corpus-grounded fixes from the hosted insights engine. Set it via the prompt above, or put ALLCHEMYAPIKEY= in the .env of the project you are scanning.

Use it outside Claude Code (any MCP client)

The same server is published to npm and the MCP Registry as @allchemylabs/aether-wcag-scanner. Any MCP client that speaks stdio can run it:

{
  "mcpServers": {
    "aether-wcag-scanner": {
      "command": "npx",
      "args": ["-y", "@allchemylabs/aether-wcag-scanner"],
      "env": { "ALLCHEMY_API_KEY": "<your beta key>" }
    }
  }
}

The first scan downloads Chromium once (about 150 MB). Without ALLCHEMYAPIKEY the scanner still runs fully offline and returns template fixes.

The 5 tools

Shortened. The full README is on GitHub.