SiteLint Auditor MCP Server
MCP server that runs SiteLint Auditor - WCAG and SiteLint Best Practices for accessibility, SEO, performance, and security audits via LLM agents.
The auditor bundle additionally supports WebMCP: when enabled it registers in-page tools on document.modelContext, so browser agents can run and inspect audits directly on a live site without this server. See WebMCP (in-page tools).
Quick start
npx @sitelint/auditor-mcp
Requires Chromium or Chrome. The MCP server automatically detects an installed system browser. If none is available, Puppeteer normally downloads Chrome during package installation; if that download was skipped, it downloads Chrome for Testing on the first audit. No browser path configuration is required.
Tools
audit_url
Audit a live URL.
{
"url": "https://example.com",
"standards": ["wcag"],
"auditTypes": ["accessibility"],
"wcagLevels": ["A", "AA"],
"wcagVersions": ["2.2"],
"wcagCriteria": []
}
audit_html
Audit raw HTML without fetching a URL. Defaults to waitUntil: "load" so image-based rules (e.g. oversized images, size calculations) see fully loaded assets. A timeout guards against hanging external resources — if the load event never fires, the audit aborts with a clear error instead of hanging. Pass waitUntil: "domcontentloaded" to skip slow assets entirely.
All filter parameters are required — pass empty arrays to skip a filter.
WCAG audit:
{
"html": "<!DOCTYPE html><html>...</html>",
"standards": ["wcag"],
"auditTypes": ["accessibility"],
"wcagLevels": ["A", "AA"],
"wcagVersions": ["2.2"],
"wcagCriteria": ["1.1.1", "1.4.3"]
}
SiteLint best practices (proprietary SEO, performance, security):
{
"html": "<!DOCTYPE html><html lang=\"en\"><head><title>Test</title></head><body></body></html>",
"standards": ["sitelint"],
"auditTypes": ["seo", "performance", "security"],
"wcagLevels": [],
"wcagVersions": [],
"wcagCriteria": []
}
Full audit (everything):
{
"html": "<!DOCTYPE html><html>...</html>",
"standards": ["wcag", "sitelint"],
"auditTypes": ["accessibility", "performance", "security", "seo"],
"wcagLevels": ["A", "AA", "AAA"],
"wcagVersions": ["2.0", "2.1", "2.2"],
"wcagCriteria": []
}
check_wcag_criterion
Check a single WCAG criterion against a URL.
{
"url": "https://example.com",
"criterion": "1.1.1"
}
Returns pass/fail with violation count.
Filter parameters
Filters are ANDed — a rule must match every provided filter to run. On audit_url filters are optional (omit or pass empty arrays to skip). On audit_html all filter parameters are required — pass empty arrays to skip.
Omit a parameter (or pass empty array) to skip that filter.
Resources
Configuration
Environment variables
SSE / HTTP transport
Run the server over Streamable HTTP instead of stdio:
AUDITOR_TRANSPORT=sse AUDITOR_PORT=3100 npm start
The server listens on 127.0.0.1:3100 and accepts MCP requests via POST /. Host and Origin headers are validated (localhost only). Graceful shutdown on SIGINT/SIGTERM closes the browser and the HTTP server.
Client config:
{
"mcpServers": {
"sitelint-auditor": {
"url": "http://127.0.0.1:3100"
}
}
}
CLI flags
auditor-mcp --bundle ./custom-bundle.js --timeout 60000 --headless false
Integration guides
opencode
Add to ~/.config/opencode/opencode.json:
{
"mcp": {
"sitelint-auditor": {
"type": "local",
"command": ["npx", "-y", "@sitelint/auditor-mcp"]
}
}
}
For a local build:
{
"mcp": {
"sitelint-auditor": {
"type": "local",
"command": ["node", "/path/to/auditor-mcp/dist/cli.js"]
}
}
}
With custom Chromium:
{
"mcp": {
"sitelint-auditor": {
"type": "local",
"command": ["npx", "-y", "@sitelint/auditor-mcp"],
"environment": {
"AUDITOR_BROWSER_PATH": "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
"AUDITOR_TIMEOUT": "60000"
}
}
}
}
Claude Desktop
Edit claude_desktop_config.json:
{
"mcpServers": {
"sitelint-auditor": {
"command": "npx",
"args": ["-y", "@sitelint/auditor-mcp"]
}
}
}
Claude Code
Plugin (recommended)
/plugin marketplace add sitelint/auditor-mcp
/plugin install auditor-mcp@sitelint
Manual
claude mcp add sitelint-auditor -- npx -y @sitelint/auditor-mcp
Codex
Plugin (recommended)
codex plugin marketplace add sitelint/auditor-mcp
codex plugin add auditor-mcp@sitelint
Manual
codex mcp add sitelint-auditor -- npx -y @sitelint/auditor-mcp
ZCode
{
"sitelint-auditor": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@sitelint/auditor-mcp@latest"
]
}
}
VS Code (Cline)
In Cline extension settings → MCP Servers:
{
"sitelint-auditor": {
"command": "npx",
"args": ["-y", "@sitelint/auditor-mcp"]
}
}
VS Code (Continue)
In ~/.continue/config.json:
{
"experimental": {
"mcpServers": {
"sitelint-auditor": {
"command": "npx",
"args": ["-y", "@sitelint/auditor-mcp"]
}
}
}
}
AnythingLLM
{
"mcpServers": {
"sitelint-auditor": {
"command": "npx",
"args": ["-y", "@sitelint/auditor-mcp"]
}
}
}
Other MCP clients
Any MCP client can connect. Use stdio transport (default) for local tools, or AUDITOR_TRANSPORT=sse with AUDITOR_PORT=3100 for remote.
Build from source
git clone <repo>
cd auditor-mcp
npm install
npm run build
# Bundle the auditor engine
cp /path/to/auditor/dist/auditor.bundle.js vendor/
cp /path/to/auditor/app/translations/en-us.json vendor/translations/
Requirements
- Node.js 20+
- Chromium or Chrome (detected automatically, or downloaded by Puppeteer during installation/on the first audit if needed)
- SiteLint Auditor bundle (vendored as
vendor/auditor.bundle.js)
How it works
- Launches headless Chromium via Puppeteer (single browser, pages capped by
AUDITOR_CONCURRENCY) - Loads the target page and waits for it to settle (bounded by
AUDITOR_TIMEOUT) - Injects the SiteLint Auditor JS bundle into the page
- Runs a single-shot audit against the current DOM state
- Formats results into a concise text report with grouping and truncation for long outputs
- Stores full JSON as a resource accessible via
auditor://report/{id}
Navigation failures, timeouts, and browser-launch errors are returned as readable messages rather than raw exceptions.
Limitations vs. embedded auditor
When SiteLint Auditor is embedded directly into a website via <script>, it watches for DOM mutations, re-tests dynamically loaded content, and provides an interactive sidebar UI. The MCP server does not do any of that — it takes a one-time snapshot of the page at the moment of injection. Content loaded after the audit starts (lazy images, infinite scroll, SPA route transitions) is not evaluated. For SPAs or pages with heavy dynamic content, consider waiting for full render before calling the tool.
WebMCP (in-page tools)
WebMCP turns the page itself into a tool server: the site exposes client-side functions with JSON schemas, and a browser agent invokes them directly in the open tab. No stdio/SSE transport, no headless browser, no server deployment.
When the auditor is embedded via <script> with the webmcp option enabled, it registers:
Enabling from page code:
auditor.config({ webmcp: true });
auditor.run();
The flag is opt-in and defaults to false. Registration is feature-detected: browsers without
document.modelContext silently skip it and the auditor behaves exactly as before.
When to use WebMCP instead of this server
- Live page state — audits SPAs, authenticated views, and content rendered after load; the server only snapshots the initial DOM (see Limitations vs. embedded auditor above).
- Fix-and-verify loop — the agent changes the page, re-runs
sitelint_run_audit, and usessitelint_highlight_issueto show the user what remains — all inside the user's tab. - Assistive and browser-agent workflows — the agent and the user share one context.
Requirements
- Chromium 146+ with WebMCP enabled (
chrome://flags/#enable-webmcp-testingin preview builds; Chrome 150+ exposes the producer API ondocument.modelContext) - Secure context (HTTPS)
- Tools are visible to same-origin consumers only; cross-origin exposure requires the
toolspermissions policy plusexposedToat registration
WebMCP complements this server rather than replacing it: headless audits of arbitrary URLs (CI,
batch checks, sites that do not embed the auditor) stay on @sitelint/auditor-mcp; in-browser
agents driving a live site use the WebMCP tools.