Image Alt Text Generator

Generate context-aware, accessible alt text for images at scale — covering e-commerce products, editorial photography, and decorative graphics.

accessibilityalt-textimagesseoa11y

Image Alt Text Generator

Writing alt text manually for hundreds or thousands of images is one of those tasks that’s easy to skip and hard to do consistently. This skill processes images in batch, generates descriptive alt text appropriate to each image’s context and purpose, and flags decorative images that should receive an empty alt="" attribute rather than a description.

TL;DR

Provide images (or image URLs) along with context about where they appear on your site. The skill returns ready-to-use alt text strings, distinguishes between informative and decorative images, and optionally outputs captions for editorial use. No network access required if you supply images directly.

What it does

Alt text isn’t one-size-fits-all. A product photo on an e-commerce page needs different alt text than the same image used as a decorative background. This skill handles that distinction:

  • Context-sensitive description generation — Produces alt text that reflects where the image appears (product listing, blog post, hero banner, data visualization) rather than just describing what’s visible. A chart gets alt text that conveys the data trend, not just “a bar chart.”
  • Decorative image detection — Identifies images that serve a purely visual/layout purpose (dividers, background textures, icon-only buttons with adjacent text labels) and marks them for alt="" so screen readers skip them appropriately.
  • E-commerce product alt text — For product images, generates structured descriptions that include product name, key attributes (color, material, size if visible), and orientation (front view, detail shot, lifestyle image) — the format that both screen reader users and Google Image Search benefit from.
  • Multilingual alt text output — When given a target locale, produces alt text in the appropriate language, accounting for right-to-left scripts and locale-specific terminology rather than direct translation.
  • Batch processing with CSV export — Accepts a list of image URLs or file paths and returns a CSV with columns for image path, suggested alt text, image type (informative/decorative), and a confidence flag for cases where the image content is ambiguous.
  • WCAG 2.1 compliance checking — Reviews existing alt text against WCAG 2.1 Level AA criteria, flagging descriptions that are too long (over 125 characters), redundant (“image of…”, “photo of…”), or missing for non-decorative images.

Best for

  • E-commerce teams with large product catalogs where every image needs accurate, keyword-relevant alt text for both accessibility and image SEO.
  • Publishers and media organizations managing editorial photo libraries where alt text needs to convey journalistic context, not just visual description.
  • Accessibility compliance teams conducting audits before a WCAG review or legal deadline — the skill can process an existing image inventory and produce a gap report.

This skill is less suited to highly specialized technical diagrams (medical imaging, engineering schematics) where domain expertise is needed to describe the content accurately. In those cases, use the skill’s output as a starting draft and have a subject matter expert review.

How to use (example)

Scenario: You run an online furniture store. You have 340 product images that currently have no alt text, and your accessibility audit flagged this as a critical issue.

Input

Images: [product-image-urls.csv with 340 rows]
Context: E-commerce product pages, furniture retailer
Product data available: Yes (product name, category, color, material from catalog)
Target locale: en-US
Output format: CSV with columns: image_url, alt_text, image_type, confidence
Flag decorative images: Yes

What the skill produces (sample rows)

image_url,alt_text,image_type,confidence
/images/sofa-oslo-grey-front.jpg,"Oslo 3-seater sofa in light grey linen, front view",informative,high
/images/sofa-oslo-grey-detail.jpg,"Close-up of Oslo sofa armrest showing linen texture and solid oak leg",informative,high
/images/divider-wave.svg,"",decorative,high
/images/sofa-oslo-lifestyle.jpg,"Oslo sofa styled in a Scandinavian living room with a floor lamp and coffee table",informative,medium
/images/badge-free-shipping.png,"Free shipping on orders over $150",informative,high

Confidence flags explained:

  • high — Image content is clear and the description is reliable
  • medium — Image is ambiguous (lifestyle shot with multiple focal points); review recommended
  • low — Image is low resolution, heavily cropped, or content is unclear; manual review required

Variations

  • Audit mode: Provide existing alt text alongside images. The skill reviews and scores each one, returning suggested improvements rather than generating from scratch.
  • Caption mode: Add output: captions to get longer, editorial-style captions (2–3 sentences) suitable for figure elements or image galleries.
  • Single image: Works just as well for one image — paste the URL and describe the page context, and you’ll get alt text in seconds.

Permissions & Risks

Required permissions: Images (read access to image files or URLs)
Risk level: Low

The skill reads image content and returns text. It does not modify images, write to your CMS, or publish anything. The primary risk is inaccurate descriptions for ambiguous images — particularly lifestyle photography where the intended focal point isn’t obvious. Always review medium- and low-confidence outputs before publishing.

A secondary consideration: privacy in images. If your image library contains photos of identifiable people (staff photos, user-generated content), be aware that the skill will describe visible individuals. Review your privacy policy before processing images of real people at scale.

Troubleshooting

  1. Alt text describes the wrong focal point in a product image
    This happens when a product image has a busy background or multiple items. Add a primary_subject field to your input: primary_subject: "Oslo sofa". The skill will anchor its description to that subject.

  2. Decorative images are being marked as informative
    Decorative detection relies on visual cues (solid colors, abstract patterns, no text). If your decorative images contain text or icons, add a decorative_patterns list to your input specifying filename patterns like divider-*, bg-*, texture-*.

  3. Alt text is too long for your CMS character limit
    Specify a max_characters: 100 constraint. The skill will prioritize the most important descriptive elements and truncate gracefully rather than cutting mid-sentence.

  4. Multilingual output uses the wrong regional variant
    Specify the full locale code rather than just the language: es-MX instead of es, or pt-BR instead of pt. This ensures the skill uses the correct regional vocabulary and avoids terms that are correct in one country but awkward or wrong in another.

  5. Existing alt text audit returns too many false positives
    If the skill flags alt text that you consider acceptable, adjust the strictness level: wcag_level: AA (default) or wcag_level: A for a more permissive check. You can also add a skip_patterns list for alt text formats your team has deliberately chosen.

  6. Batch processing stalls on large image sets
    Process in chunks of 50–100 images rather than submitting all 340 at once. Large batches can hit memory limits depending on image file sizes. The CSV output format makes it easy to merge results from multiple runs.

Alternatives

  • Azure Computer Vision API — Microsoft’s image analysis API generates captions and tags programmatically. More powerful for custom integrations but requires developer setup and API billing management.
  • Google Cloud Vision API — Excellent for label detection and OCR in images. Better suited to technical pipelines than editorial workflows; outputs raw labels rather than natural-language alt text.
  • Manual accessibility audit — A human accessibility specialist reviewing images against WCAG criteria. Slowest option but highest accuracy for complex or sensitive content. Best used alongside this skill for low-confidence outputs.

Skills:

  • Content Brief — Plan image requirements and alt text strategy as part of your editorial brief
  • SEO Keyword Cluster — Identify keywords to incorporate into product image alt text for image SEO
  • Web Search — Research accessibility standards and WCAG updates

Guides:

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