A mechanism is provided for enforcing accessible content development. The mechanism enforces accessible content development by accessing a tag library descriptor for each of a plurality of markup tags for web content authoring where the tag library descriptor notes one or more tag sub-elements required for accessibility. The mechanism analyzes each markup tag in a piece of web content by comparing the tag library descriptor accessibility requirements to sub-elements included with each markup tag to determine whether all required accessibility sub-elements are present. The mechanism generates an error message if all required accessibility sub-elements of a markup tag are not present.