How to Show Cursor Exactly What to Fix

Cursor is excellent when the change is in code you can name. Visual polish - spacing, hierarchy, wrong state on a dense dashboard - turns into telepathy. Screenshots help; marked screenshots help more.

The failure mode is familiar: you describe "the secondary button under the chart," Cursor edits a different secondary button, and you spend the next turn undoing. Marks collapse that loop.

Use a system overlay when the bug is not limited to an embedded browser preview. Capture the real window, mark regions, and paste image + notes into Cursor chat or your preferred agent CLI.

• Reproduce the viewport and theme customers see.
• Mark every distinct issue as its own number.
• Paste once with clear constraints ("no refactors").
• Re-annotate only remaining issues after the first pass.
• If you know the file, mention it once; let the image own the visual truth.

In-product visual tools are great for the surfaces they cover. A desktop overlay covers Electron apps, native clients, Figma, staging on another monitor, and anything Cursor cannot embed. Casso is built for that second set while remaining agent-agnostic if you leave Cursor for Claude Code the same afternoon.

You do not have to pick one forever. Many developers use Cursor's built-in tools for pure web previews and Casso for everything that lives outside that sandbox.

• Is the UI in the broken state (not a happy-path mock)?
• Does each number have a concrete expected outcome?
• Did you exclude secrets and customer PII from the frame?
• Is the agent constrained to the right files or components?