Trylasso

Trylasso is a free Mac app for drawing directly on your screen. Use it to annotate the parts of your display that matter, then pass those marks to AI agents that take screenshots as input. The creator originally built it for personal use and shared it publicly.

Instead of describing a region in text, you can mark it on screen and let the annotated screenshot direct the agent's attention. The site describes these annotations as simpler pointers for screenshot-based agent inputs.