Does your viewport meta tag let mobile agent browsers render your page correctly?
Without a proper viewport tag, AI agents on mobile see a zoomed-out desktop layout with clipped content.
What this signal tests
We check whether your HTML head contains a meta viewport tag declaring width=device-width and initial-scale=1, which tells mobile browsers to render at the device's actual width rather than a fake 980 pixel desktop. We also check that you have not disabled pinch-zoom via user-scalable=no or maximum-scale less than 5, both of which violate accessibility guidelines.
Why it matters for your visibility in AI
Mobile agent browsers and Google's mobile-first crawler render your pages at mobile widths. Without a viewport tag, they see a desktop layout shrunk to fit a phone screen, which mis-measures Core Web Vitals, clips text, and makes the agent click coordinates fall on the wrong elements. If your site lacks a viewport tag, an AI agent asked to fill in a contact form may click empty whitespace because the form elements rendered tiny and offset from where it expected. The second half of the check is accessibility. Setting user-scalable=no fails WCAG 2.2 Success Criterion 1.4.4 (Resize Text) at Level AA, because users with low vision cannot pinch-zoom to read your content. This blocks compliance, alienates users, and is now flagged by Google's own mobile usability reports.
Pass criteria at a glance
| Criterion | Passes when |
|---|---|
| viewport meta exists with required directives and no zoom-disabling. |
How we test it
We parse your homepage HTML head for a meta tag with name=viewport. We then check the content attribute for two required directives: width=device-width (renders at the device's true width) and initial-scale=1 (starts at 100 percent zoom). We also flag user-scalable=no and maximum-scale below 5, both of which disable pinch-zoom and fail accessibility rules. All three conditions must be satisfied for a pass.
Show technical detection method
Parse <meta name=viewport>; require width=device-width AND initial-scale=1; absence of user-scalable=no and maximum-scale<5.
If your site fails: how to fix it
- Add the standard viewport tag to your HTML head: <meta name="viewport" content="width=device-width, initial-scale=1">. This is the recommended default for every modern responsive site.
- Remove any user-scalable=no or maximum-scale=1 directives if you find them. These were a common anti-pattern on early mobile sites and now actively harm accessibility and AI agent reliability.
- If you use a CMS or framework (WordPress, Next.js, Astro, Ghost), check whether the theme or layout already includes a viewport tag. Most modern themes do; older ones often do not.
- Verify in Chrome DevTools by opening device emulation mode and confirming the page renders at the expected mobile width. If it looks like a tiny desktop layout, the viewport tag is missing or wrong.
- Re-run the AI Ready Test to confirm the viewport tag is detected with the required directives.
Quick facts
| Maturity | ESTABLISHED |
|---|---|
| Weight | medium |
| Category | Performance |
Primary sources
Related signals
Frequently asked questions
Why is disabling pinch-zoom bad?
It locks out users with low vision who rely on pinch-zoom to read text, failing WCAG 2.2 Level AA. It also breaks AI agents that emulate mobile and rely on default zoom behaviour to find clickable elements. There is almost never a good reason to set user-scalable=no.
Does this affect my Google ranking?
Yes. Google's mobile-first indexing assumes a working viewport tag. Missing or broken viewport setup is flagged as a mobile usability issue in Search Console and can suppress rankings on mobile queries, which is the majority of search traffic.
What if I want a fixed-width desktop layout?
Use responsive CSS with media queries instead of disabling the viewport. A fixed-width layout on mobile delivers a terrible experience to both humans and AI agents. Mobile traffic is now the majority of web traffic - design for it first.
How long does this take to fix?
Minutes. Adding the meta tag is one line of HTML; the harder work is ensuring your CSS responds correctly to the new mobile width, which most modern themes already do. Test with Chrome device emulation before deploying.
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