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Accessibility MCP Server

by jbuchan

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

πŸ” 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

πŸ€– MCP Integration

  • Three main tools exposed to AI agents:

    • test_accessibility: Run accessibility tests

    • get_test_results: Retrieve saved test results

    • list_test_results: List all available test files

πŸ“Š Rich Reporting

  • Human-readable text reports

  • Raw JSON data for programmatic access

  • Screenshot capture capability

  • Detailed violation summaries with remediation guidance

πŸ›‘οΈ Security & Validation

  • URL validation and sanitization

  • Configuration parameter validation

  • Graceful error handling

  • Safe browser isolation

Installation

# Clone and install dependencies npm install # Install Playwright browsers npx playwright install # Build the project npm run build

Usage

Starting the MCP Server

# Development mode npm run dev # Production mode npm run build && npm start

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 test

  • wcagLevel (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:

{ "url": "https://example.com", "wcagLevel": "AA", "wcagVersion": "2.1", "browser": "chromium", "includeScreenshot": true }

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

src/ β”œβ”€β”€ server/ # MCP server implementation β”‚ β”œβ”€β”€ index.ts # Main entry point β”‚ └── mcpServer.ts # MCP protocol handlers β”œβ”€β”€ accessibility/ # Core testing engine β”‚ └── tester.ts # Playwright + axe-core integration β”œβ”€β”€ types/ # TypeScript type definitions β”‚ └── index.ts # Interface definitions └── utils/ # Utility modules β”œβ”€β”€ fileOutput.ts # Result file management └── validation.ts # Input validation and sanitization

Development

Project Structure

  • src/server/: MCP server implementation and entry points

  • src/accessibility/: Core accessibility testing logic

  • src/types/: TypeScript type definitions

  • src/utils/: Utility functions for validation and file I/O

  • outputs/: Generated test results and screenshots

  • tests/: 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

  1. Fork the repository

  2. Create a feature branch

  3. Make your changes

  4. Add tests for new functionality

  5. Submit a pull request

Support

For issues and questions:

  1. Check the documentation

  2. Review existing GitHub issues

  3. Create a new issue with detailed information

Deploy Server
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security - not tested
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license - not found
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quality - not tested

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.

  1. Overview
    1. Features
      1. πŸ” Comprehensive Accessibility Testing
      2. πŸ€– MCP Integration
      3. πŸ“Š Rich Reporting
      4. πŸ›‘οΈ Security & Validation
    2. Installation
      1. Usage
        1. Starting the MCP Server
        2. Available Tools
      2. Architecture
        1. Development
          1. Project Structure
          2. Configuration
          3. Error Handling
        2. Output Formats
          1. Text Reports
          2. JSON Data
        3. Security Considerations
          1. Cloud Deployment (Future)
            1. Dependencies
              1. License
                1. Contributing
                  1. Support

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