MCP CSS Validator MCP Tool
validate_css(url) — ask an AI assistant to validate a page's CSS: invalid values, unknown properties, overridden declarations, and more.
validate_css(url)
Fetches a public page, collects every inline <style> block and linked stylesheet it references, and runs the combined CSS through the same checks as the CSS Validator web tool.
Requires a Pingfloat API key. See MCP Server setup if you don't have one yet.
Try it
Validate the CSS on https://example.comThe assistant calls validate_css and returns a score, grade, and a list of error/warning/info issues, plus which stylesheets were checked.
Parameters
| Parameter | Type | Description |
|---|---|---|
url | string, required | The public page URL whose stylesheets should be validated. |
What it checks
- Invalid hex colors and malformed values
- Unknown or misspelled property names
- Unquoted multi-word font-family values
- Duplicate or overridden declarations within a rule
- Rules relying heavily on
!important var()usage without a fallback value
Frequently asked questions
Does it check external stylesheets, or just inline styles?
Both — it collects every inline <style> block and every linked <link rel="stylesheet"> on the page (up to 12 linked stylesheets) and validates the combined CSS.
Is there a limit on how many times I can call it?
10 per hour on a free account, 50 per hour on Free+ — shared with the other check and QR tools, tracked per API key.