Enables cross-browser accessibility testing using Firefox as one of the supported browser engines for WCAG compliance auditing
Accessibility MCP Server
A Model Context Protocol (MCP) server for automated accessibility testing using Playwright and axe-core against WCAG standards.
Overview
This server provides AI agents (LLMs) with the ability to perform comprehensive accessibility audits on websites. It leverages industry-standard tools to deliver detailed reports on WCAG compliance violations and recommendations.
Features
π Comprehensive Accessibility Testing
Full WCAG 2.1/2.2 compliance checking (A, AA, AAA levels)
Cross-browser testing (Chromium, Firefox, WebKit)
Real browser automation with Playwright
axe-core accessibility engine integration
π€ MCP Integration
Three main tools exposed to AI agents:
test_accessibility
: Run accessibility testsget_test_results
: Retrieve saved test resultslist_test_results
: List all available test files
π Rich Reporting
Human-readable text reports
Raw JSON data for programmatic access
Screenshot capture capability
Detailed violation summaries with remediation guidance
π‘οΈ Security & Validation
URL validation and sanitization
Configuration parameter validation
Graceful error handling
Safe browser isolation
Installation
Usage
Starting the MCP Server
The server communicates via stdin/stdout following the MCP protocol specification.
Available Tools
test_accessibility
Run an accessibility test on a website.
Parameters:
url
(required): Website URL to testwcagLevel
(optional): 'A', 'AA', or 'AAA' (default: 'AA')wcagVersion
(optional): '2.1' or '2.2' (default: '2.1')browser
(optional): 'chromium', 'firefox', or 'webkit' (default: 'chromium')includeScreenshot
(optional): boolean (default: false)
Example:
get_test_results
Retrieve saved accessibility test results.
Parameters:
fileName
(required): Name of the test result file
list_test_results
List all available test result files.
No parameters required.
Architecture
Development
Project Structure
src/server/
: MCP server implementation and entry pointssrc/accessibility/
: Core accessibility testing logicsrc/types/
: TypeScript type definitionssrc/utils/
: Utility functions for validation and file I/Ooutputs/
: Generated test results and screenshotstests/
: Test suites (planned)
Configuration
The server accepts various configuration options:
WCAG Levels: A, AA, AAA
WCAG Versions: 2.1, 2.2
Browsers: Chromium, Firefox, WebKit
Timeouts: 1s to 5 minutes
Viewports: 320x200 to 4000x4000 pixels
Error Handling
The server implements comprehensive error handling:
URL validation and sanitization
Browser initialization failures
Network timeout handling
File I/O error recovery
Graceful MCP protocol error responses
Output Formats
Text Reports
Human-readable accessibility reports including:
Executive summary with violation counts
Detailed violation descriptions with remediation steps
Element-specific failure information
WCAG success criteria references
JSON Data
Machine-readable results containing:
Complete axe-core results
Test metadata and configuration
Structured violation data
Performance metrics
Security Considerations
URL validation prevents testing of local/private addresses
Browser sandboxing through Playwright
Input sanitization for all parameters
Safe file I/O operations
Process isolation
Cloud Deployment (Future)
This server is designed for eventual cloud deployment with:
Container support (Docker)
Environment-based configuration
Database integration for result storage
API rate limiting
Authentication and authorization
Dependencies
@modelcontextprotocol/sdk: MCP protocol implementation
playwright: Browser automation framework
@axe-core/playwright: Accessibility testing integration
axe-core: Accessibility rules engine
typescript: Type safety and development tooling
License
MIT License - see LICENSE file for details.
Contributing
Fork the repository
Create a feature branch
Make your changes
Add tests for new functionality
Submit a pull request
Support
For issues and questions:
Check the documentation
Review existing GitHub issues
Create a new issue with detailed information
local-only server
The server can only run on the client's local machine because it depends on local resources.
Enables AI agents to perform comprehensive accessibility audits on websites using Playwright and axe-core against WCAG standards. Provides detailed compliance reports with violation summaries and remediation guidance across multiple browsers.