Edit an existing canvas
When to use: The user wants to modify a canvas they already have, in place. “Add a footer to my deck”, “change the headline on slide 2”, “fix the date in the resume”. The original canvas is mutated.Tool call
Destructive — call this out to the user
canvas_id mutates the source canvas. Five edits → five revisions of the same canvas. If the user wants variations of the canvas while keeping the original clean, use fill-template.md or rebrand-template.md instead.
Mutually exclusive
canvas_id, template_canvas_id, and conversation_id cannot be combined.
canvas_id+template_canvas_id→ tool error.template_canvas_id+conversation_id→ tool error.canvas_id+conversation_id→ no error, butcanvas_idis silently ignored. The agent uses the conversation’s canvas.
Iterating in conversation
For follow-up tweaks (“now make the title bigger”, “add a third bullet”) on the same canvas, passconversation_id from the previous response instead of canvas_id. The agent keeps full context of prior turns.
See also
create-new-design.md— start from scratch insteadfill-template.md— produce a new canvas that mirrors the source structure../references/gotchas.md#conversations-vs-canvases-vs-remixes— full mutual-exclusion matrix