At a minimum, you must add a document title to the metadata in the InDesign document. The document title will carry over to other formats, such as PDF, EPUB, and HTML. InDesign allows you to add many other types of metadata, but none of the others are particularly relevant to accessibility.

To add a document title to the metadata, go to File > File Info, then type the title into the “Document Title” field.

Screenshot of the file info option in the File menu

Screenshot of the Document Title field in the metadata dialog