Alt Text Is How a Machine Reads Your Images, and Most of Yours Say Nothing

An image is opaque to anything that cannot see it, which includes a screen reader, a search crawler, and a language model summarizing your page. The alt attribute is the one line of text that tells all three what the picture is. When it is missing, the image might as well not be on the page as far as any of them is concerned.

The finding says some of your images have no alt text. That is genuinely worth fixing, and it is also the single most over-automated field on the web, so the interesting question is not whether to write it but what to write.

Why this matters for AI traffic

Google is unusually direct about the alt attribute’s importance: it is “the most important attribute when it comes to providing more metadata for an image,” and it “also improves accessibility for people who can’t see images on web pages.” Two audiences, one line of text, and the second one is the reason this is not optional: alt text is an accessibility requirement before it is ever an SEO tactic.

For retrieval, the logic is the same as everywhere else in AI search. A model assembling an answer works from text. An image with no alt text contributes nothing to what your page is understood to be about; an image with a precise description adds a fact the model can use and, when the answer wants an illustration, a reason to reach for yours. This is not a large lever. It is a cheap one, and it compounds across every image on a page that matters.

What good alt text looks like

Google supplies both the rule and the anti-pattern, so there is no need to guess.

The rule is to describe the image in context. Their example is alt="Dalmatian puppy playing fetch": what it is, doing what, in a few plain words. Not “image”, not “puppy.jpg”, not “photo1”. A person who could not see it should learn what they missed.

The warning is against the reflex that SEO gave everyone. Google cautions against “filling alt attributes with keywords (also known as keyword stuffing) as it results in a negative user experience and may cause your site to be seen as spam,” and the example they hold up as wrong is alt="puppy dog baby dog pup pups puppies doggies". That is not a description, it is an incantation, and it earns the spam label precisely because it helps neither the person using a screen reader nor the machine trying to understand the page.

So the target is one honest sentence, and their summary is the whole method: “focus on creating useful, information-rich content that uses keywords appropriately and is in context of the content of the page.”

Two edge cases the finding will not distinguish for you. A purely decorative image, a divider, a background flourish, should have an empty alt attribute (alt=""), which tells a screen reader to skip it rather than announce noise. And a chart or a screenshot with information in it needs alt text that conveys the information, not just the label: “revenue up 40 percent from 2024 to 2025”, not “bar chart”.

When is it worth fixing, and when should you skip it?

Fix it when:

• The image carries meaning: a product photo, a diagram, a chart, anything a reader would be worse off missing.
• The page matters commercially or is one you want cited. Alt text is cheap insurance on exactly those.

Give it an empty alt when:

• The image is decorative. alt="" is the correct answer, not a failure to fill it in. A description of a spacer graphic is noise a screen reader has to read aloud.

Do not over-invest when:

• The image is one of hundreds in an archive nobody visits. Alt text is worth writing where the page is worth reading.
• You would be tempted to stuff keywords to make the count go up. A blank alt is better than a spammy one. Google says so directly.

The honest tradeoff: this is low-effort and real, both for accessibility (where it is an obligation, not a tactic) and for how machines read your page. It is also the field most likely to be filled with garbage by an automated pass. I would write real descriptions on the images that carry meaning, mark the decorative ones empty, and never let a tool stuff keywords into the attribute to clear the finding.

Writing a true sentence about a specific image is a judgment a machine makes badly, because it cannot know why the image is on the page. Get AI Traffic applies the edit through set_content once the description is decided. Note the limit: the value of an alt attribute is whether it honestly describes the image, and nothing but a look at the image and the page around it can supply that.

Frequently asked questions

Is alt text a ranking factor? It is the primary metadata Google uses to understand an image, and it drives image search. More importantly it is an accessibility requirement, which makes it worth doing regardless of the ranking question. Treat it as table stakes, not as a lever you crank.

What makes alt text good? One plain sentence describing the image in the context of the page. Google’s own example is “Dalmatian puppy playing fetch”. Say what it is and what is happening, the way you would to someone who cannot see it.

Should I put keywords in my alt text? Only when the keyword is what the image shows. Google warns that stuffing alt attributes with keywords reads as spam and can hurt you, and shows “puppy dog baby dog pup pups puppies doggies” as the thing to avoid. Describe the image; if a keyword is the honest description, fine, but do not force it.

What about decorative images? Give them an empty alt attribute (alt=""). That tells assistive technology to skip them. An empty alt is a correct answer, not a missing one, and a tool that flags it as a defect is wrong.

Can I just have AI generate all my alt text? For a rough first pass on a huge library, maybe, but check it. A generator describes pixels, not purpose, and the whole value of alt text is that it says why the image is there. On the images that matter, write the sentence yourself.

Sources

• Google Search Central: Google Images SEO best practices
• W3C WAI: An alt Decision Tree