Pixel-level accessibility audit using Claude vision. Catches issues that DOM scanners miss: icon contrast (1.4.11), focus visibility (2.4.7), "looks like a button but isn't" (4.1.2), text rendered as images (1.4.5), visual hierarchy mismatches. Takes a URL, opens it in a headless browser, screenshots, and runs vision-based detection. Complements scan_page — run both for full coverage. Sign in with a free WebAbility account for vision and full audits (sign in by connecting https://mcp.webability.io/mcp/auth, or run `webability login`). Fair-use rate limits apply. NOTE: on this HOSTED server, localhost and private addresses are refused — it runs in our cloud and cannot reach your machine. Two ways to scan a local dev server: run the MCP locally (`npx -y @webability/mcp`, simplest — nothing leaves the machine), or open a tunnel (`webability-tunnel --port 3000`) and pass its URL as `url` together with the printed secret as `tunnel_secret`.