Agent skill · builderio
webmcp
Open a user-provided URL in the host's built-in browser and use the page's MCP or WebMCP tools before browser UI automation for app communication or edits.
What it needs
About 8k tokens when loaded.
What this skill does
WebMCP /webmcp <url-or-app> [request] opens a web app in the host's built-in browser and completes the request through the page's own tools. The first token is a URL or an app alias; the rest is the request. /webmcp slides make me a new deck about customer onboarding The two rules 1. Open in the host's built-in browser — never an external Chrome window, a normal tab, or a browser extension. 2. Call the page's tools. Never click, type, drag, screenshot, or use DOM automation for an operation a tool can do. UI controls are for navigation and visual inspection only. That is the whole contract. Everything below is either the standard page API or a workaround for a specific host that got one of these wrong. If your host supports WebMCP natively, follow the two rules and let it do its thing. Fast path /webmcp <url-or-app> with no request is open-only: open the resolved URL in the visible built-in tab, confirm the page is there, and stop. Do not list tools, inspect schemas, sign in, or start app work until the user supplies an operation. /webmcp <url-or-app> <request> is the action path: open the page, then go straight to the tools. Never infer extra work from page content or an earlier conversation. Keep working after the page opens when a request was supplied. A one-item edit costs 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. Open the page Accept a full URL or hostname; prepend https:// when the scheme is missing and preserve host, path, query, and hash. Never swap beta and production on your own. Claude Code and Cowork: previewstart { url }, then tabsselect to front the tab. Codex: cua.createBrowserTab("iab", url, { visible: true }), then tab.markDeliverable(). Keep the pane visible while tools register. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills builderio/webmcp