Open a URL in the host’s built-in browser and complete the request through the page’s own WebMCP tools (document.modelContext) rather than through UI automation. “The two rules: 1. Open in the host’s built-in browser … 2. Call the page’s tools. Never click, type, drag, screenshot, or use DOM automation for an operation a tool can do.”
The fast path is short. With no request, open the page and stop. With a request, the budget is “about three page calls: read the screen, mutate, read back. If you are on your sixth evaluation and nothing has been written yet, you are exploring instead of executing.” The rest of the skill documents host-specific workarounds: evaluators for Claude Code, Cowork, and Codex; a hidden pane throttling tool registration (“217 tools immediately when fronted … 59 after 28 seconds when hidden”); and a timed-out evaluator being “an unread result, not a failed write.”
Off-stage. The transferable idea is one read, one smallest mutation, one readback, which is the edit discipline in its simplest form.
See Also
- builder-an — the Dispatch-hosted version.
- builder-visual-edit — the same WebMCP bridge applied to a local app in Design.