Does your mobile site show the same content, metadata, and structured data as desktop?
AI Overviews crawl your mobile version first - any gaps between mobile and desktop become invisible content in AI answers.
What this signal tests
We compare the page a mobile crawler sees with the page a desktop crawler sees. We check the title, meta description, headings, canonical URL, hreflang annotations, structured data blocks, and main content length on both versions. Differences greater than ten percent are flagged because mobile-first crawlers will use the mobile version as the source of truth for both classic search and AI Overviews.
Why it matters for your visibility in AI
Google's mobile-first indexing means the mobile version of your site is what Google ranks and what feeds Google's AI Overviews - and most other AI assistants inherit that same mobile-first crawl. If your mobile pages are stripped-down versions of desktop (less content, fewer headings, missing schema, hidden FAQ sections), the AI sees only the stripped-down version, and your richest content is invisible. This is a hidden problem for sites that built mobile as an afterthought. The desktop site is beautifully written, but the mobile version skips a section here, drops a structured data block there, hides a FAQ behind a tap-to-reveal. Every gap is content that AI assistants cannot cite, and competitors with proper responsive design fill the void.
Pass criteria at a glance
| Criterion | Passes when |
|---|---|
| Fields equivalent within 10%; metadata identical. |
How we test it
We fetch each sampled page twice - once with a desktop browser user agent, once with the Googlebot-Smartphone user agent - and compare key fields side by side: the page title, meta description, the H1 through H3 headings, the canonical URL, hreflang annotations, every structured data block in JSON-LD, and the overall length of the main content. Any field that differs by more than ten percent or is missing on one variant is flagged.
Show technical detection method
Fetch URL with desktop UA and Googlebot-Smartphone UA; compare title, meta description, H1-H3, canonical, hreflang, JSON-LD blocks, main-content length. Flag deltas >10%.
If your site fails: how to fix it
- Adopt a responsive design that serves the same HTML to all devices and adapts layout with CSS. This is the modern default and eliminates parity issues by construction.
- If you serve different HTML by device (dynamic serving or separate m. subdomain), set a Vary: User-Agent response header so CDNs and crawlers know to cache variants separately.
- Audit any content that is hidden on mobile. If users have to tap to reveal sections, those sections must still be present in the HTML and not added by a later JavaScript call. Lazy-loaded content tied to user interaction is invisible to crawlers.
- Make sure structured data JSON-LD blocks are emitted identically on both mobile and desktop. Removing schema on mobile to save bytes is a common but costly mistake.
- Check that no noindex meta tag is added on mobile templates. Some old responsive themes accidentally noindex the mobile variant, with predictably disastrous results.
- Re-run the AI Ready Test to confirm the deltas are below the ten percent threshold.
Quick facts
| Maturity | ESTABLISHED |
|---|---|
| Weight | high |
| Category | Crawlability |
Primary sources
Related signals
Frequently asked questions
Is a separate mobile site (m.example.com) still acceptable?
It works but is fragile. Maintaining two HTML codebases inevitably leads to drift, and the parity issues this signal catches are usually worst on separate mobile sites. Responsive design - one HTML, adapted with CSS - is the recommended pattern in 2026 and removes a whole class of problems.
What if my mobile version legitimately has less content because users prefer it?
User preference is real, but the trade-off is invisibility in AI answers. Better to keep the content in the HTML and hide it behind tabs or collapsible sections that the crawler can read but the user does not see by default. That preserves both UX and AI visibility.
Why does Google care about mobile parity?
Most users now browse on mobile, so Google indexes the mobile version of your site preferentially. AI assistants that feed off Google's index inherit this priority. The result is that the mobile version is the canonical version for both classic search and AI - if it is stripped down, your authority is stripped down too.
How do I test what Googlebot-Smartphone sees on my page?
Google's URL Inspection tool in Search Console shows you the rendered mobile view as Googlebot saw it. Browser dev tools can also override the user agent for spot checks. The AI Ready Test automates this comparison across a sample of your pages.
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