Website monitoring · No. 11
Page SEO tags check
In short
SEO tags are behind-the-scenes elements in your page code that visitors barely notice but search engines and AI assistants read first: title, meta description, H1, robots directives, canonical, hreflang, and Open Graph. One mistake, such as an accidental noindex, removes a page from Google and from AI answers while the website keeps working normally.
Contents
What are SEO tags?
SEO tags are technical elements in your page code that describe the page to search engines, social networks, and AI assistants. Most of them live in the <head> section or are sent by the server along with the page, so visitors don’t see them. The exception is the H1 heading: it’s the main visible heading on the page itself.
These elements decide whether a page makes it into search, what title and description it’s shown with, and what a link to it looks like in Telegram or on Facebook.
| Element | Where it lives | What it does |
|---|---|---|
| Title | <title> | The page name in the browser tab and the main candidate for the title in search results |
| Meta description | <meta name="description"> | A short summary Google may use to build the snippet |
| H1 | Page body | The main visible heading |
| Meta robots | <meta name="robots"> | Permissions for search engines: whether to index the page and whether to show a snippet |
| X-Robots-Tag | HTTP response header from the server | The same permissions as meta robots, but set on the server — you won’t see them in the page code |
| Canonical | <link rel="canonical"> | Which URL counts as the main one if the page is available at several |
| Hreflang | <link rel="alternate" hreflang> | Which language versions of the page exist |
| Open Graph | <meta property="og:…"> | The title, description, and image for link previews on social media and in messaging apps |
What can an SEO tag mistake cost you?
The most dangerous mistake is accidentally blocking indexing. A noindex directive in meta robots or in the X-Robots-Tag header tells Google outright to drop the page from search:
“Do not show this page, media, or resource in search results.”
Meanwhile, the website opens as usual, so the problem only gets noticed when search traffic drops. X-Robots-Tag is sneakier than the meta tag: it’s set in the server configuration, so it simply isn’t in the page code.
The second most dangerous mistake is a wrong canonical. If it points to a different URL — say, the home page — Google may treat the page as a copy and show the other one in search. Google calls rel="canonical" “a strong signal that the specified URL should become canonical” and recommends putting a canonical on the canonical page itself, pointing to itself (Google documentation).
Hreflang mistakes don’t break the website, but they mix up language versions: a visitor may land on a page in the wrong language. Google ignores the markup if the pages don’t link to each other:
“If two pages don’t both point to each other, the tags will be ignored.”
An overly long title or description won’t get you penalized, but Google truncates the title link in search results, “typically to fit the device width,” and builds the title link automatically from the title, H1, og:title, and other prominent text on the page (Google documentation). So the title you see in search may not be the one you wrote.
Without proper Open Graph tags, a link in Telegram, WhatsApp, or on Facebook shows up as a bare URL or with a random image. The Open Graph specification lists four required properties: og:title, og:type, og:image, and og:url (ogp.me).
Visibility in AI answers
How do SEO tags affect your visibility in AI answers?
Google’s AI answers — AI Overviews and AI Mode — don’t need any special tags. Google says plainly, “There are no additional requirements to appear in AI Overviews or AI Mode,” and the requirement for a page is the same as for regular search:
“To be eligible to be shown as a supporting link in AI Overviews or AI Mode, a page must be indexed and eligible to be shown in Google Search with a snippet, fulfilling the Search technical requirements.”
The takeaway is simple: meta robots and X-Robots-Tag decide whether a page can show up in Google’s AI answers at all. noindex removes it from both search and AI Overviews. According to Google’s documentation, the nosnippet directive applies to all result formats and “will also prevent the content from being used as a direct input for AI Overviews and AI Mode,” while max-snippet “will also limit how much of the content may be used as a direct input for AI Overviews and AI Mode” (Google documentation).
The other tags work indirectly. Canonical determines which URL Google treats as the main one for the index, so a mistake there can keep the right page out of the index — and out of AI answers. Google uses the title, H1, and og:title to build a page’s title link, and the more accurately they describe the content, the easier it is for search and AI to understand what the page is about.
How do SEO tags affect Performance Max ads?
Directly, if your Performance Max campaign has text customization turned on — the feature formerly called “automatically created assets.” It writes ad headlines and descriptions based on your website:
“Google AI generates headlines and descriptions from your landing page content, domain, and current ads.”
Google limits text length: headlines can be up to 30 characters, and long headlines and descriptions up to 90 (Google Ads Help). And, according to Google, “Google reviews and refreshes these assets at least every 48 hours to ensure continued accuracy” (Google Ads Help), so changes on your page reach your ads quickly.
Google doesn’t disclose which page element each piece of text comes from. From hands-on campaign management, the picture looks like this:
- Title — the main source for short headlines of up to 30 characters: the system uses it whole or without the brand name.
- H1 — most often becomes a long headline of up to 90 characters or gets combined with the title.
- Meta description — raw material for descriptions of up to 90 characters: used as is, shortened, or rephrased by generative AI.
- H2–H3 and benefit lists — phrases like “Free shipping on orders over $50” or “12-month warranty” become ready-made selling points for additional headlines and descriptions.
When someone searches, the system matches their intent against these texts and shows the most relevant combination. The bottom line: an unnoticed change to your title, description, or H1 — after a theme or plugin update or a bulk edit — also changes what your ads say.
Why do SEO tags break?
Almost always after website changes made for a completely different reason:
- Moving from staging. Indexing is blocked on the staging site — in WordPress, it’s a separate checkbox in Reading settings — and nobody turns it off after launch.
- A theme or SEO plugin update. The new template builds the title and description its own way, and the H1 disappears or the logo becomes the H1.
- Server or CDN settings. An
X-Robots-Tag: noindexheader added for the staging domain ends up on the live one. - A template-wide canonical. Someone hard-coded a canonical pointing to the home page into the template — and now it’s on every page.
- A new language version. The page was translated, but hreflang was updated in only one language, so the links are no longer reciprocal.
- Auto-generated titles. The CMS glues the product name to its description, and the title balloons to several hundred characters.
How do you spot an SEO tag problem?
Most mistakes don’t show up on the website itself but in search results or messaging apps. Here are the typical symptoms and what to do about them:
| What you see | Possible cause | What to do |
|---|---|---|
| The page disappeared from Google but still opens | noindex in meta robots or X-Robots-Tag | Remove the block in your CMS or on the server, then request recrawling in Search Console |
| Search shows a different page from your website | The canonical points to a different URL | Point the canonical to the page itself |
| The title in search is cut off or doesn’t match your title tag | The title is too long, vague, or repetitive | Shorten it and make it unique to the page |
| The description in search is a random chunk of text | The description is missing, the same on every page, or doesn’t match the content | Write a separate description for every important page |
| Links in Telegram or on Facebook have no image | og:image is missing or the image is unavailable | Add og:image with a working URL |
| Visitors land on the wrong language version | Hreflang is incomplete or not reciprocal | Each version should point to itself and to all the others |
How to check SEO tags yourself
All you need is a browser and a few free tools. Check every important page this way after any website update:
- Open the page and press
Ctrl+U(Cmd+Option+Uon a Mac) to view its source code. UseCtrl+Fto find<title,name="description",name="robots",rel="canonical",hreflang, andog:. - Find
<h1in the code and make sure the heading describes the page content and isn’t, say, just the company name from the logo. - Check X-Robots-Tag: open developer tools (
F12), go to the Network tab, reload the page, select the first request, and look at Response Headers. - In Google Search Console, use the URL Inspection tool: it shows whether indexing is allowed and which URL Google chose as canonical.
- For Open Graph, paste the page URL into Meta’s Sharing Debugger to see what the link preview will look like.
- Or use the FullCheckApp “Page SEO tags check” and get the results in a clear visual format.
For one page, this takes a few minutes. On a website with dozens of pages that gets updated regularly, manual checks quickly become a chore that keeps getting put off.
If you chose the last option, you’ve already made the right call: the check runs automatically, and you’ll be the first to know about any warning or critical issue.
What FullCheckApp checks
Every day, FullCheckApp checks the SEO tags on your home page and on the inner pages you’ve added to monitoring. Each element in the report has a value and a flag: green means OK, yellow means worth a look, and red means a problem.
- Title — length, with a 30–60 character guideline. Google doesn’t set a hard limit; this is a practical range where the title usually isn’t truncated.
- Description — length, with a 70–160 character guideline.
- H1 — present on the page or missing.
- Meta robots and X-Robots-Tag — the values of both and the bottom line: indexing allowed or blocked.
- Canonical — the URL and whether it matches the page URL.
- Hreflang — how many language versions are listed and which ones.
- Open Graph —
og:title,og:description,og:image,og:url,og:type,og:site_name, andog:locale.
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en, esThis check rates the quality of your tags at the time of the check. Changes — when a title, description, or H1 gets rewritten — are tracked by separate checks: title tag change monitoring, meta description change monitoring, and H1 heading change monitoring. Page status according to Google itself is covered in the Google page indexing check article.
FAQ
What’s the ideal title tag length?
Google doesn’t set a title length limit, but it truncates title links in search results, usually to fit the screen width. A practical guideline is 30–60 characters: a title that length is usually shown in full. More important than length is that the title is unique, briefly describes the page content, and doesn’t repeat the same words.
Do I need a meta description if Google may replace it anyway?
Yes. Google usually builds the snippet from the page text, but it uses the meta description when it describes the page more accurately. Write a separate description for every important page: according to Google, identical descriptions across your whole website don’t help.
How many H1 headings should a page have?
One. MDN, Mozilla’s web developer reference, says the HTML standard allows multiple H1s, but the best practice is a single H1 that describes the page content. Google doesn’t penalize multiple H1s — Google’s John Mueller has said so. Still, Google builds the title link from the title, the main visible heading, and heading elements, so one clear H1 makes its choice easier.
What’s the difference between meta robots and robots.txt?
robots.txt decides whether a page can be crawled, while meta robots decides whether it can be indexed and shown in search. If a page is blocked in robots.txt, Google can’t read its code and won’t see the noindex, so the indexing block won’t work.
Does noindex remove a page from AI Overviews?
Yes. To appear in AI Overviews and AI Mode, a page must be indexed, and noindex blocks it from Google Search. The nosnippet directive also applies to AI Overviews and AI Mode, and max-snippet limits how much text those answers can take from the page.
Sources
- Google Search Central — Influencing title links in Google Searchdevelopers.google.com/search/docs/appearance/title-link
- Google Search Central — Control your snippets in search resultsdevelopers.google.com/search/docs/appearance/snippet
- Google Search Central — Robots meta tag, data-nosnippet, and X-Robots-Tag specificationsdevelopers.google.com/search/docs/crawling-indexing/robots-meta-tag
- Google Search Central — How to specify a canonical URLdevelopers.google.com/search/docs/crawling-indexing/consolidate-duplicate-urls
- Google Search Central — Tell Google about localized versions of your pagedevelopers.google.com/search/docs/specialty/international/localized-versions
- Google Search Central — AI features and your websitedevelopers.google.com/search/docs/appearance/ai-features
- Google Search Central — SEO Starter Guidedevelopers.google.com/search/docs/fundamentals/seo-starter-guide
- The Open Graph protocologp.me/
- MDN Web Docs — <h1>–<h6>: HTML section heading elementsdeveloper.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/Heading_Elements
- Google Search Central (YouTube) — Multiple H1 Headings: How to Handle Them for SEO & Accessibility?www.youtube.com/watch?v=zyqJJXWk0gk
- Google Ads Help — About Performance Max campaignssupport.google.com/google-ads/answer/10724817?hl=en
- Google Ads Help — About text assets for Performance Max campaignssupport.google.com/google-ads/answer/14528373?hl=en
- Google Ads Help — About text customization in Performance Max campaignssupport.google.com/google-ads/answer/10724897?hl=en
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