Alt Text Coverage: How to Evaluate Effectively

You'll learn to assess alt text across three dimensions: presence, accuracy, and conciseness. By the end you'll be able to categorize issues using a Critical, Major, and Minor severity framework. This lesson gives you a framework for providing actionable feedback that references specific WCAG criteria and explains user impact. Learning Objective: By the end of this lesson, learners will be able to evaluate alt text quality by applying a three-dimension assessment model and a three-tier severity framework to prioritize fixes. Transcript The Three Dimensions of Alt Text The evaluation process starts with three specific dimensions that determine whether your alternative text effectively replaces visual content for screen reader users. Experienced practitioners know that checking for mere compliance is insufficient, so they assess presence, accuracy, and conciseness to ensure every non-decorative image carries meaningful descriptive weight. This holistic approach prevents the common mistake of focusing solely on whether an attribute exists, which often leads to technically compliant but unusable text that fails the user. The first dimension is presence, which checks if alt attributes are included for all non-decorative images according to WCAG accessibility guidelines. Every meaningful image must have an alternative text equivalent, ensuring that no visual information is left behind for users who cannot see the screen. When teams treat presence as a baseline requirement, they create a stable foundation for accessibility, allowing them to focus on the quality of the description rather than its existence. Accuracy is the second dimension, evaluating whether the text correctly describes the image’s content, function, or context. This aligns with Nielsen’s Visibility of System Status heuristic, because the alt text must accurately reflect the system’s visual state to the user. If a button image says "Submit button image" instead of "Submit form," it fails to describe the action, misleading the user about what will happen next. Conciseness ensures the description is brief enough for screen reader efficiency but detailed enough to convey necessary information. This balances Morville’s usability facet, where efficiency and clarity are paramount, preventing users from wading through excessive detail that disrupts their flow. Strong work typically stays under one hundred twenty-five characters for simple images, providing just enough context without overwhelming the auditory interface. That establishes the core dimensions of evaluation; the next section walks through how to spot the specific signals of strong versus weak work. Key Points: Presence: Check if alt attributes are included for all non-decorative images per WCAG guidelines. Accuracy: Evaluate if text correctly describes content, function, or context, aligning with Nielsen’s Visibility of System Status. Conciseness: Ensure descriptions are brief enough for screen reader efficiency but detailed enough to convey necessary information. Signals of Strong vs. Weak Work Here’s how this works in practice when you’re scanning a live interface for quality signals. You’re looking for contextual relevance, which means the alt text complements the surrounding content rather than repeating it. If a caption already describes the image, strong work keeps the alt text brief or null to avoid redundancy. This alignment with Dr. David Travis’s User Focus areas ensures the user’s goal is met without unnecessary friction. Functional clarity is another strong signal, especially for interactive elements like links or buttons. The alt text should describe the action or destination, such as "Submit form," instead of the visual artifact, like "Submit button image." This distinction matters because screen reader users need to know where they are going, not what the button looks like. It transforms a visual cue into a navigational aid that supports task completion efficiently. On the flip side, generic labeling is a glaring signal of weak work that provides no meaningful information. Seeing "image1.jpg" or just "photo" in the code tells you nothing about the content or its purpose. This violates WCAG guidelines by failing to offer an equivalent alternative to the visual experience. It leaves screen reader users guessing, which breaks the flow of their interaction with the page. Over-description is another common failure where the alt text includes excessive detail unnecessary for understanding. For instance, describing every pixel in a complex chart slows down navigation and frustrates users who just need the key takeaway. This disrupts the efficiency that Morville’s usability facet prioritizes, turning a quick glance into a long read. The work that takes longer up front to edit returns faster decisions on the other side for the user. These signals help you categorize issues before applying the severity framework we’ll discuss next. The patterns you spot now determine whether an issue is critical, major, or minor in the upcoming evaluation steps. Key Points: Strong Work Signal: Contextual relevance where alt text complements rather than repeats surrounding captions. Strong Work Signal: Functional clarity for links/buttons (e.g., 'Submit form' instead of 'Submit button image'). Weak Work Signal: Generic labeling like 'image1.jpg' or 'photo' which provides no meaningful information. Weak Work Signal: Over-description including excessive detail unnecessary for understanding, such as describing every pixel in a chart. Applying the Severity Framework Consider your last project where you audited image accessibility, because applying a severity framework transforms that chaotic pile of issues into a prioritized action plan. You need to categorize findings by their impact on the user experience, which aligns with Magnus Revang’s UX Wheel to balance usability, desirability, and feasibility. Start by auditing a sample of images in your current project, categorizing issues by severity to ensure you address the most damaging barriers first. This structured approach prevents you from wasting time on minor nitpicks while critical access points remain broken for screen reader users. Critical severity includes missing alt text for meaningful images or incorrect descriptions that mislead users, which directly violates WCAG success criteria. These issues must be addressed immediately because they completely block understanding or provide false information, creating a broken experience for users who rely on auditory feedback. When you encounter a functional image with no text, or a chart described as "photo," mark it as critical because the system status is invisible or misleading. Experienced practitioners treat these violations as urgent defects, knowing that accessibility compliance requires every meaningful visual element to have an accurate text equivalent. Major severity covers issues like overly long descriptions or redundant text that impedes efficiency but does not completely block understanding. These problems slow down navigation and frustrate users, even though the core information remains accessible, so they require attention without the same emergency response as critical errors. If you find a paragraph of text describing a simple icon, categorize it as major because it violates conciseness principles and disrupts the user's flow through the interface. The field notes that while these issues don't break the experience, they degrade the quality of interaction significantly enough to warrant a dedicated fix cycle. Minor severity includes stylistic inconsistencies or slight inaccuracies that do not significantly impact usability, allowing you to batch these fixes for later optimization. These might include capitalization differences or minor phrasing tweaks that don't change the meaning, so they can wait until critical and major issues are resolved. By separating these small adjustments from high-impact barriers, you maintain a realistic roadmap that respects development resources while still moving toward full compliance. Use this framework to balance usability, desirability, and feasibility when planning fixes, ensuring your team tackles the right problems at the right time. Now that you have the tools to categorize and prioritize these issues, the next section walks through how to translate those findings into actionable feedback for your design team. Key Points: Critical Severity: Missing alt text for meaningful images or incorrect descriptions that mislead users; violates WCAG success criteria. Major Severity: Overly long descriptions or redundant text that impedes efficiency but does not completely block understanding. Minor Severity: Stylistic inconsistencies or slight inaccuracies that do not significantly impact usability. Prioritization: Use this framework to balance usability, desirability, and feasibility when planning fixes. Actionable Feedback and Transfer Tomorrow, you could start by auditing a sample of images in your current project, categorizing issues by Critical, Major, or Minor severity. This moves the work from abstract theory to concrete practice, grounding your evaluation in the specific realities of your interface. When you provide feedback, reference specific WCAG criteria like 2.1.1 Non-text Content rather than offering vague complaints about poor accessibility. Citing the exact standard gives designers a clear target and transforms subjective criticism into an objective, actionable requirement that they can address with confidence. You should suggest concrete alternatives to guide the revision process effectively. For instance, if you encounter a generic label like image1.jpg, propose rewriting it to Graph showing quarterly sales growth. This specific example demonstrates how to replace empty placeholders with descriptive text that conveys actual meaning. Providing the solution alongside the problem saves time and ensures the designer understands the level of detail required for effective alt text. Always explain the user impact to reinforce why these changes matter for accessibility. Note that over-description slows down screen reader navigation, which creates friction for users who rely on assistive technology. By connecting technical violations to real-world usability consequences, you help your team prioritize fixes that genuinely improve the experience. This approach ensures that every alt text decision supports efficient, inclusive interaction rather than just checking a compliance box. That brings the lesson full circle, back to the moment you’ll first put this evaluation protocol into practice with your own designs. Key Points: Reference specific WCAG criteria (e.g., 2.1.1 Non-text Content) rather than vague complaints. Suggest concrete alternatives, such as rewriting 'image1.jpg' to 'Graph showing quarterly sales growth.' Explain user impact, noting that over-description slows down screen reader navigation. Next Step: Audit a sample of images in your current project, categorizing issues by Critical, Major, or Minor severity.