test_accessibility
Evaluate webpage accessibility compliance with WCAG standards using Axe-core. Analyze specific accessibility tags to identify and address issues effectively.
Instructions
Test a webpage for accessibility issues using Axe-core
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| tags | No | Optional array of accessibility tags to test (e.g., "wcag2a", "wcag2aa", "wcag21a") | |
| url | Yes | URL of the webpage to test |
Implementation Reference
- src/index.ts:46-65 (registration)Registration of the 'test_accessibility' tool in the MCP ListTools handler, defining its name, description, and input schema.
{ name: 'test_accessibility', description: 'Test a webpage for accessibility issues using Axe-core', inputSchema: { type: 'object', properties: { url: { type: 'string', description: 'URL of the webpage to test', }, tags: { type: 'array', items: { type: 'string' }, description: 'Optional array of accessibility tags to test (e.g., "wcag2a", "wcag2aa", "wcag21a")', default: ['wcag2aa'] } }, required: ['url'], }, }, - src/index.ts:193-238 (handler)The main handler function for 'test_accessibility' tool. Launches Puppeteer browser, navigates to the provided URL, runs Axe accessibility analysis (optionally filtered by tags), formats results, and returns as MCP content.
async testAccessibility(args: any) { const { url, tags } = args; if (!url) { throw new McpError( ErrorCode.InvalidParams, 'Missing required parameter: url' ); } let browser; try { browser = await puppeteer.launch({ headless: true, args: ['--no-sandbox', '--disable-setuid-sandbox'] }); const page = await browser.newPage(); // Set a reasonable viewport await page.setViewport({ width: 1280, height: 800 }); await page.goto(url, { waitUntil: 'networkidle0', timeout: 0 }); // Run axe analysis const axe = new AxePuppeteer(page); if (tags && tags.length > 0) { axe.withTags(tags); } const result = await axe.analyze(); return { content: [ { type: 'text', text: JSON.stringify(this.formatResults(result), null, 2), }, ], }; } finally { if (browser) { await browser.close(); } } } - src/index.ts:772-798 (helper)Helper function used by the test_accessibility handler to format AxeResults into a structured JSON response with violations, passes, and metadata.
private formatResults(result: AxeResults) { return { violations: result.violations.map((violation: Result) => ({ id: violation.id, impact: violation.impact || 'unknown', description: violation.description, help: violation.help, helpUrl: violation.helpUrl, affectedNodes: violation.nodes.map((node: NodeResult) => ({ html: node.html, target: node.target, failureSummary: node.failureSummary || '' })) })), passes: result.passes.length, incomplete: result.incomplete.length, inapplicable: result.inapplicable.length, timestamp: result.timestamp, url: result.url, testEngine: { name: result.testEngine.name, version: result.testEngine.version }, testRunner: result.testRunner, testEnvironment: result.testEnvironment, }; }