What do you need to know about annotation tools? Basically, the annotation tool helps you mark a specific object in a picture or document, fill PDF form, or even sign a document. Though Microsoft Snip & Sketch has annotation features, it is limited. Unfortunately, Windows OS does not have a default powerful annotation tool. Is there an annotation tool for windows 10? Apart from basic tools like: highlighter, sticky notes, stamps, text box, type writer, strikeout, under line, and free hand pencil, it has other advanced annotation tools as well. This software includes basic PDF markup and comment tools. PDF-XChange Viewer is another PDF annotation software, available for free. Frequently Asked Questions Which is the best free annotation software for pdf?