Should your alt text really describe the image rather than optimize your keywords?

Why does Google emphasize the factual description of images?

The answer boils down to one word: accessibility. Alt text was created for screen readers used by visually impaired individuals. When a screen reader reads 'cheap performance lightweight women's running shoes' instead of a coherent description, the user experience collapses.

Google also uses alt tags to understand the visual context of a page. Its visual AI (Google Lens, Cloud Vision) is already analyzing images with increasing accuracy, but alt text remains a strong semantic signal to link the image to surrounding content. A relevant alt reinforces the thematic coherence of the page — a keyword-stuffed alt muddles it.

Does this directive change anything for Google Images SEO?

Yes and no. Google Images has been indexing visuals for years by cross-referencing multiple signals: file name, caption, surrounding text, and of course, the alt tag. However, the algorithm has become mature enough to detect inconsistencies.

If your image shows a beige leather sofa and the alt says 'buy cheap Scandinavian design furniture with fast delivery,' Google immediately picks up the mismatch. The engine won’t harshly penalize you, but it will simply ignore this signal as unreliable. The result: you lose an opportunity to enhance relevance without gaining anything in return.

What constitutes a 'useful' description according to Google?

A useful description answers the question: 'If I couldn't see this image, what should I know to understand its role in the content?' This involves mentioning concrete visual elements: colors, objects, people, actions, spatial context.

For example, for an e-commerce product photo, 'Beige full grain leather corner sofa with left chaise' far surpasses 'Modern design comfortable living room sofa.' The first description contains factual attributes that help Google categorize the image for the right queries ('beige leather corner sofa,' 'left chaise') without forcing it.

• The alt must be specific: 'Golden retriever playing with a red ball in a garden' rather than 'happy dog'
• No repetition of the title or H1: the alt text complements the context, it does not duplicate it
• Reasonable length: 10 to 15 words maximum — screen readers cut off after ~125 characters
• No 'image of' or 'photo of': it's redundant, screen readers already announce it's an image
• Integrate the keyword naturally only if the image truly justifies it

Is this statement consistent with observed practices in the field?

Absolutely. The audits we conduct reveal that sites that over-optimize alt tags do not perform better in Google Images — sometimes even worse. The engine now seems capable of scoring the semantic quality of an alt, and artificial text lowers this score.

On the other hand, sites that employ factual and varied descriptions (no generic template duplicated across 200 products) achieve higher-quality Google Images traffic. The correlation is not always spectacular, but it exists. And it makes sense: a precise alt attracts more specific queries, leading to traffic with a better conversion rate.

In which cases does this rule not fully apply?

Purely decorative images — separators, backgrounds, illustrative icons without informative value — should have an empty alt (alt=""). This signals to screen readers to skip the element without verbalizing it. Google understands this signal very well and doesn't seek any information there.

For complex infographics, an alt that is too short is insufficient. You should combine: a synthetic alt ('Infographic: evolution of the organic market in France 2015-2023') + a complete textual transcription below or in an accordion. Google indexes both, and the user gets the information even if the image doesn't load.

What nuances should be applied to this directive?

Mueller says 'not all the keywords on the site,' which is true. But he doesn't say 'no keywords at all.' If your image indeed shows the product or concept you're targeting, the keyword should naturally appear in the description. This is even desirable.

The trap is excess. An alt like 'Women's Nike Air Zoom lightweight breathable running shoes for marathon trail road' is on the edge. Too long, too marketed. Better to say: 'Nike Air Zoom Pegasus 40 women, side view.' Concrete, factual, with the product reference that is objectively useful. [To be verified]: Google has never published quantitative data on the actual impact of an optimized alt vs pure descriptive alt. Field A/B tests show marginal gains, rarely exceeding 5-10% additional Images traffic.

What concrete steps should you take to audit your alt tags?

Start by extracting all the alt tags from your site with Screaming Frog (Images > Export). Sort by frequency: if you see the same generic text like 'product image' 200 times, it’s a template to break. Each image should have a unique alt or be marked as decorative (empty alt).

Next, filter out alts longer than 100 characters and those containing more than 3 occurrences of the same keyword. These two cases are classic red flags of over-optimization. Rewrite them as factual descriptions: color, material, angle of view, visible action.

What mistakes should you absolutely avoid when writing alts?

Never copy-paste the product title or H1 into the alt. Google detects semantic duplication and derives little value from it. The alt should provide supplementary information. If your H1 says 'Osprey Atmos 65L Hiking Backpack,' your alt can specify 'Osprey Atmos 65L green backpack, front view with adjustable straps.'

Avoid passive or vague formulations: 'product that can be used for' or 'illustration showing the concept of.' Be direct. And above all, never stuff an alt with synonyms or variations of keywords — Google Lens recognizes the object anyway, so you gain nothing by overloading the textual signal.

How can you check if your alts meet Google's expectations?

Use Google Search Console > Performance > 'Images' tab. If you see impressions but an abnormally low CTR (<1%), it’s often a sign that your images are showing up for irrelevant queries — a classic symptom of poorly targeted alts. Also, compare the volume of Images traffic before/after rewriting: a gain of 15-20% over 3 months is a good indicator.

You can also test manually: search your target keywords in Google Images and see if your visuals appear. If you’re invisible while your text content ranks well, it’s likely that your alts do not reinforce the semantic coherence of the page. A thorough audit with a tool like Oncrawl or Botify can reveal patterns invisible to the naked eye.

• Extract all alt tags with Screaming Frog and identify duplicates
• Rewrite generic or over-optimized alts into factual descriptions (10-15 words max)
• Mark decorative images with alt="" to avoid noise
• Ensure that each alt provides supplementary information to the title/caption
• Monitor Google Images traffic in Search Console after modification
• Integrate keywords naturally only when the image justifies it