Deterministic local test page

WebMCP Cart Lab

A visible cart with read-only and mutating tools for validating discovery, approval, execution, and dynamic toolchange handling.

Detecting WebMCP…

The page is checking the browser API.

WebMCP is unavailable. Enable chrome://flags/#enable-webmcp-testing, relaunch Chrome, and reload this page. The manual cart still works, but an agent cannot discover its tools.

Manual controls remain visible

Catalog

Visible tool result

Cart

Items 0 Total $0.00

Expected discovery

Registered tools

get_cart read-only
add_item requires approval
clear_cart requires approval

Use “Expose discount tool” to register apply_discount dynamically.