--- title: "Your alt text passes automated checks. That doesn’t mean it’s any good." url: https://daily.dev/posts/your-alt-text-passes-automated-checks-that-doesn-t-mean-it-s-any-good--yl2nudg6n source_url: https://github.blog/engineering/user-experience/your-alt-text-passes-automated-checks-that-doesnt-mean-its-any-good type: article source: "GitHub Blog" published: 2026-08-24T21:01:36.244Z updated: 2026-08-24T21:02:02.249Z tags: ["webdev", "llm", "github", "accessibility"] reading_time: 10 upvotes: 4 comments: 1 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Your alt text passes automated checks. That doesn’t mean it’s any good. **[GitHub Blog](https://daily.dev/sources/ghblog)** · 10 min read · 4 upvotes · 1 comments ## Summary GitHub built an alt text quality plugin for its Accessibility Scanner to catch alt text that passes automated checks but is still unhelpful, such as filenames, placeholders, or generic words. Five deterministic string-based rules run by default with no AI dependency, while an opt-in rule sends image content and page context to a vision model via GitHub Models for subjective judgments. The post details engineering decisions: catching repeated alt text based on visual layout rather than DOM order, tuning the model prompt with a decision procedure and anti-nitpick rules to avoid flooding developers with false positives, and privacy/cost tradeoffs like redacting URLs before sending data to the model. It closes with limitations, including no support for SVGs, canvas, or aria-label, and a reminder that passing automated checks is not the same as real accessibility conformance. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why do most automated alt text checkers miss alt text like alt="IMG_2847.png" or alt="3/5 stars" repeated across icons? Most checkers only verify that an accessible name exists, not whether it says anything useful, because a quality-oriented rule with false positives tends to get disabled by teams. As a result, filenames, placeholders like TODO, generic words like image or logo, and repeated captions across adjacent images all pass presence checks despite being unhelpful to screen reader users. _Developers hardening accessibility pipelines can follow tooling design tradeoffs like this on daily.dev._ ### How can I detect repeated alt text on a webpage without flagging unrelated images that happen to share the same label? Group images by their on-screen position rather than their order in the DOM. Compare bounding boxes and only treat two images as part of the same repeated run when the gap between their boxes is small relative to the boxes' own size, since a header logo and footer logo can share alt text in markup while being nowhere near each other visually. _Teams building accessibility scanners can track layout-aware detection techniques like this on daily.dev._ ### How do you stop a vision model from flagging every image's alt text as needing improvement? Use a decision procedure instead of an open-ended prompt: walk four ordered steps (decorative, redundant with caption, functional, informative), stop at the first match, and force structured output with reasoning generated before the verdict. Also add explicit anti-nitpick rules that trust the author's framing, since asking a model 'could this be better?' always yields yes. _Anyone tuning LLM-based review tools can follow prompt design lessons like these on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@heracles2756** · 0 upvotes > A smart, pragmatic approach—combining deterministic checks with optional AI judgment makes accessibility tooling more useful without sacrificing developer trust or privacy ## Similar posts on daily.dev - [Developing an alt text button for images on my website](https://daily.dev/posts/developing-an-alt-text-button-for-images-on-my-website-iksmaxxzh) · Lobsters · 1 upvotes · 0 comments --- Tags: [#webdev](https://daily.dev/tags/webdev), [#llm](https://daily.dev/tags/llm), [#github](https://daily.dev/tags/github), [#accessibility](https://daily.dev/tags/accessibility) [View this post on daily.dev](https://daily.dev/posts/your-alt-text-passes-automated-checks-that-doesn-t-mean-it-s-any-good--yl2nudg6n)