docs/mcp.md said that with nothing being dragged, remote press_key c
chose the tool bound to C and f ran the shortcut bound to F. Remote
press_key sends the key event without the letter it types, and the app
runs single-key shortcuts only from the typed letter, so neither runs.
The Arc tool, Selection marquee and grid paragraphs now say what
headless press_key does with these letters and point remote callers to
select_tool or invoke_menu.