Sketch

  • Desktop app
  • All plans
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What it does

A drawing canvas inside the agent composer. Open a blank canvas to sketch a mockup, a wireframe or a diagram, or open an image already in the composer to annotate it: circle the bug, draw an arrow, highlight a region, add text. Attach to message exports the drawing as a PNG and drops it in the composer's file tray; it travels with your next message like any attached image, so an agent whose model reads images sees the drawing instead of parsing a paragraph of description.

Where to find it

  • The Sketch button in the composer toolbar of any agent (tooltip "A sketch is worth a thousand words").
  • On an image thumbnail in the composer tray: the pencil button Edit in sketch canvas.
  • In the file preview of an image: Annotate.

How to use it

  1. Click Sketch. A fullscreen canvas opens with the rectangle tool already active, ready to frame an element.
  2. Draw: freehand, rectangles, ellipses, arrows, lines, text.
  3. Click Attach to message (disabled until something is drawn). The PNG appears as a numbered thumbnail (File #N) in the tray.
  4. Write your prompt and send: the image goes with the message.

Annotating an existing image: drop a screenshot in the composer (or capture one with Screenshot to Agent), click the pencil on its thumbnail. The image is the background layer; draw on top, attach, and the annotated version replaces the original thumbnail so the agent never receives the image twice. Closing a modified canvas asks for confirmation.

Settings

  • composerHiddenActions (global, Settings > Composer > Composer toolbar buttons): hide the Sketch button if you never use it.

Agent tools (MCP)

None. The sketch reaches the agent as a plain image attachment.

Providers

All providers whose model accepts image input: the attachment is a standard PNG passed by path, with no provider-specific logic. A text-only model receives the file path without being able to see it.

Mobile

Not available on the mobile companion. The phone can attach photos and screenshots to the focused desktop agent, without an annotation canvas.

Limits

  • Sketches are saved locally in your home folder, outside the project, and purged after seven days: they are context for one message, not documents to keep.
  • SVG files cannot be annotated (vector, not rasterizable); the pencil is hidden for them.
  • If the canvas fonts fail to load, text falls back to system fonts; drawings are unaffected.

Common questions

  • Does the agent really see my sketch? Yes, as long as its model accepts images (Claude Code, Codex and the other multimodal CLIs).
  • Can I re-edit a sketch? Yes: any image in the tray, including an annotated one, reopens in the canvas via the pencil.
  • Do I need Excalidraw, Figma or a screenshot tool? No: the canvas is inside the composer, no export, no drag back in.
  • Is anything uploaded? The PNG is sent to the agent with your message, like any attached file, and nowhere else.

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