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.

Quick start

npx @sitelint/auditor-mcp

Requires Chromium (installed automatically by Puppeteer).

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.

Parameter	Values	Example
standards	wcag, sitelint	["wcag"]
auditTypes	accessibility, performance, security, seo	["accessibility", "seo"]
wcagLevels	A, AA, AAA, best_practices	["A", "AA"]
wcagVersions	2.0, 2.1, 2.2	["2.2"]
wcagCriteria	WCAG criterion numbers	["1.1.1", "1.4.3"]

Omit a parameter (or pass empty array) to skip that filter.

Resources

URI	Description
auditor://standards	Supported WCAG criteria with levels
auditor://report/{id}	Full JSON report from a previous audit

Configuration

Environment variables

Variable	Default	Description
AUDITOR_BROWSER_PATH	Puppeteer default	Custom Chromium/Chrome path
AUDITOR_CONCURRENCY	3	Max concurrent audit pages (hard cap)
AUDITOR_TIMEOUT	30000	Navigation/render timeout (ms)
AUDITOR_HEADLESS	true	Set false to see browser
AUDITOR_TRANSPORT	stdio	stdio or sse
AUDITOR_PORT	3100	Port for SSE transport

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

Flag	Env equivalent
--browser <path>	AUDITOR_BROWSER_PATH
--concurrency <n>	AUDITOR_CONCURRENCY
--timeout <ms>	AUDITOR_TIMEOUT
--headless <bool>	AUDITOR_HEADLESS
--bundle <path>	—
--transport <stdio | sse>	AUDITOR_TRANSPORT
--port <n>	AUDITOR_PORT

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"]
    }
  }
}

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"]
      }
    }
  }
}

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 (auto-downloaded by Puppeteer, or point to existing via AUDITOR_BROWSER_PATH)
• SiteLint Auditor bundle (vendored as vendor/auditor.bundle.js)

How it works

1. Launches headless Chromium via Puppeteer (single browser, pages capped by AUDITOR_CONCURRENCY)
2. Loads the target page and waits for it to settle (bounded by AUDITOR_TIMEOUT)
3. Injects the SiteLint Auditor JS bundle into the page
4. Runs a single-shot audit against the current DOM state
5. Formats results into a concise text report with grouping and truncation for long outputs
6. 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.