# Webmcp

Open a user-provided URL in the host's built-in browser and use the page's MCP or...

- Repository: https://github.com/BuilderIO/skills (4626 stars)
- Category: Design
- License: MIT
- Last updated: 2026-10-28
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add BuilderIO/skills --skill webmcp -g -a claude-code -y`
Codex: `npx skills add BuilderIO/skills --skill webmcp -g -a codex -y`
Cursor: `npx skills add BuilderIO/skills --skill webmcp -g -a cursor -y`
Gemini CLI: `npx skills add BuilderIO/skills --skill webmcp -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add BuilderIO/skills`

## Description

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.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# 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

The rest: https://github.com/BuilderIO/skills/blob/HEAD/skills/webmcp/SKILL.md