wcag-mcp
WCAG MCP Server for Agentic Systems - Powered by Official W3C Data with Full Understanding Documentation
A Model Context Protocol (MCP) server providing comprehensive access to WCAG 2.2 guidelines, techniques, glossary terms, and complete Understanding documentation for every success criterion. Works both locally (stdio) and remotely (Netlify Functions).
Features
Complete WCAG 2.2 Coverage - All 87 success criteria with full details
Full Understanding Documentation - Intent, benefits, examples, and resources for every SC
Techniques Library - 400+ techniques (sufficient, advisory, failure patterns)
Glossary - 101 official WCAG term definitions
Version Tracking - See what's new in WCAG 2.2
What's New: Understanding Documentation
This server now includes complete Understanding documentation parsed from the official W3C WCAG Understanding documents. For every success criterion, you get:
Brief Summary - Goal, what to do, and why it's important
Intent - Detailed explanation of the purpose and rationale
Benefits - Who benefits and how
Examples - Real-world examples of implementation
Resources - Curated list of tools and references
No more following external links - everything you need is right in the MCP response!
Available Tools (20 total)
Features
Complete WCAG 2.2 Coverage - All 87 success criteria with full details
Full Understanding Documentation - Intent, benefits, examples, and resources for every SC
Techniques Library - 400+ techniques (sufficient, advisory, failure patterns)
ACT Test Rules - 87+ standardized accessibility test rules
Glossary - 101 official WCAG term definitions
Version Tracking - See what's new in WCAG 2.2
What's New: Understanding Documentation
This server now includes complete Understanding documentation parsed from the official W3C WCAG Understanding documents. For every success criterion, you get:
Brief Summary - Goal, what to do, and why it's important
Intent - Detailed explanation of the purpose and rationale
Benefits - Who benefits and how
Examples - Real-world examples of implementation
Resources - Curated list of tools and references
No more following external links - everything you need is right in the MCP response!
Available Tools (20 total)
Core WCAG Tools
Tool | Description |
| Lists all four WCAG 2.2 principles (Perceivable, Operable, Understandable, Robust) |
| Lists WCAG 2.2 guidelines, optionally filtered by principle number (1-4) |
| Lists success criteria with optional filters by level (A/AA/AAA), guideline, or principle |
| Gets just the normative success criterion text and exceptions without Understanding docs |
| Gets comprehensive details including full Understanding documentation (intent, benefits, examples) |
| Gets full details for a specific guideline including all its success criteria |
| Searches success criteria by keyword in titles and descriptions |
| Gets all criteria for a conformance level, optionally including lower levels |
| Returns counts of success criteria grouped by level, principle, or guideline |
Technique Tools
Tool | Description |
| Lists techniques, filter by technology (html, aria, css, pdf, general) or type |
| Gets details for a specific technique by ID (e.g., "H37", "ARIA1", "G94") |
| Gets all techniques (sufficient, advisory, failure) for a success criterion |
| Searches techniques by keyword |
| Gets failure patterns (common mistakes) for a success criterion |
Glossary Tools
Tool | Description |
| Gets the definition of a WCAG term (e.g., "programmatically determined") |
| Lists all 101 WCAG glossary terms |
| Searches the glossary by keyword |
Enhanced Context Tools
Tool | Description |
| Lists all 9 success criteria added in WCAG 2.2 |
| Gets comprehensive context: SC + techniques |
| Returns server information and statistics |
Data Source
This server uses official data from the W3C WCAG Repository:
WCAG JSON: Published WCAG 2.2 JSON
Understanding Docs: Parsed from official W3C Understanding HTML files in the submodule
Statistics
4 Principles - Perceivable, Operable, Understandable, Robust
13 Guidelines - Organized under principles
87 Success Criteria - Levels A (32), AA (24), AAA (31)
400+ Techniques - HTML, ARIA, CSS, PDF, General, and more
101 Glossary Terms - Official WCAG definitions
Installation
Updating WCAG Data
To pull the latest WCAG data and Understanding documentation:
The build process:
Updates the W3C WCAG git submodule to the latest version
Fetches the latest WCAG 2.2 JSON data from W3C
Parses all Understanding documentation from HTML files
This runs automatically during npm install.
Configure your IDE
Add this to your Claude Desktop MCP settings:
Deploy to Netlify
This project is configured to deploy as a Netlify Function.
Deploy via GitHub
Push this repository to GitHub
Connect it to Netlify via the Netlify dashboard
Netlify will automatically build and deploy
Using the Remote Server
Once deployed, configure your Claude Desktop MCP settings to use the remote server:
Replace your-site.netlify.app with your actual Netlify URL.
Project Structure
Attribution
WCAG data from the W3C WCAG Repository (W3C Document License).
This software includes material copied from or derived from Web Content Accessibility Guidelines (WCAG) 2.2 https://www.w3.org/TR/WCAG22/. Copyright © 2023 W3C® (MIT, ERCIM, Keio, Beihang).
License
MIT