Alt text is the main way that visually impaired individuals "see" the images on your page or post. Use Clariti to run an Alt Text Campaign to find and fix missing descriptions on your images.
First, you'll need to make sure that you have selected the column filter "alt text missing".
Next, you'll want to filter by "alt text missing (count)" greater than 1.
This will give you a list of all posts that have at least 1 missing alt text.
You can add these to a campaign or you can handle them one by one.
Once you click on a post with at least one missing alt text, scroll down and you'll see the list of images and their alt text.
Note: some themes may use decorative images that do not need alt text