webmcp

name	webmcp
description	Discover and interact with WebMCP-enabled websites. Use when Codex needs to find websites exposing browser-native WebMCP tools, query the webmcp.cool directory API, inspect tool schemas, probe arbitrary URLs for WebMCP support, or use a Playwright-controlled browser runtime to list and execute navigator.modelContextTesting tools on a page.

WebMCP

Use this skill to discover WebMCP-enabled websites and, when a compatible browser runtime is available, interact with their page-exposed tools.

Workflow

1. Discover candidate websites through the webmcp.cool directory.
2. Inspect the target site's tool names, descriptions, kind, and inputSchema.
3. Open the target website in a WebMCP-capable browser runtime.
4. List tools from the live page before executing anything.
5. Execute read-only tools first. Ask before write/action tools or any sensitive flow.
6. Report clearly whether a failure happened in directory discovery, browser capability detection, tool listing, or tool execution.

Directory Discovery

Use the WebMCP Directory API before browser interaction:

node scripts/webmcp-directory.mjs search checkout
node scripts/webmcp-directory.mjs lookup https://store.nekuda.ai
node scripts/webmcp-directory.mjs site store.nekuda.ai
node scripts/webmcp-directory.mjs tool store.nekuda.ai search_products

Load references/webmcp-api.md for endpoint details and response shapes.

Playwright Runtime

Use scripts/webmcp-playwright.mjs when the task requires live website interaction:

node scripts/webmcp-playwright.mjs probe https://store.nekuda.ai
node scripts/webmcp-playwright.mjs list https://store.nekuda.ai
node scripts/webmcp-playwright.mjs call https://store.nekuda.ai search_products '{"query":"hats","max_results":3}'

The runtime requires Playwright and a Chrome/Chromium build with WebMCP testing enabled. Prefer setting WEBMCP_CHROME to Chrome Canary/Beta when bundled Playwright Chromium does not expose WebMCP:

export WEBMCP_CHROME="/Applications/Google Chrome Canary.app/Contents/MacOS/Google Chrome Canary"
node scripts/webmcp-playwright.mjs list https://store.nekuda.ai --headed

Load references/playwright-runtime.md for runtime setup, command options, and troubleshooting.

Safety Rules

Treat directory tool kinds as the first safety signal when available:

• read: Can be used for discovery and data retrieval.
• write: May mutate page state, carts, filters, user input, or local state. Ask before calling unless the user explicitly requested that action.
• action: May navigate, authenticate, submit, purchase, open checkout, or start a side-effectful flow. Ask before calling unless explicitly requested.

Before invoking a tool:

• Confirm the live page lists the tool through navigator.modelContextTesting.listTools().
• Validate arguments against the tool's inputSchema.
• Ask first when the name or description implies payment, checkout, purchase, booking, authentication, form submission, deletion, cancellation, returns, reviews, or order changes, even if the directory marks it as read.
• Use --allow-side-effects only after user intent is explicit.
• Use --allow-unknown only when the site is not in the directory and the user accepts the risk.

Fallbacks

If the directory knows the site but Playwright cannot see navigator.modelContextTesting, say the site appears WebMCP-enabled in the directory but the local browser runtime cannot execute WebMCP tools.

If a browser runtime is unavailable, still provide directory-backed recommendations and exact tool schemas. Do not pretend tool execution happened.

If the user asks for best-effort website automation without WebMCP, use normal Playwright locators as a separate fallback and label it as DOM automation, not WebMCP.