Navya Agarwal’s agent went from two-to-five seconds per action down to under 500 milliseconds once it stopped screenshotting pages and started reading the accessibility tree instead. That’s the case for WebMCP, the standard Chrome opened to trial in June, and for Shopify switching agent tools on by default across every Liquid storefront on 5 August. The two hosts work through what that speed costs: a declared tool registry that nothing obliges to stay true to the interface it describes, a concern formal enough that WebKit’s standards tracker records outright opposition to it while Mozilla stays neutral.
They also follow where the evidence actually points. Shopify’s own shipped tools call the same code path the storefront theme already uses, which undercuts the fear more than it confirms it, and a single-author arXiv paper on Affora argues better markup might make a separate agent registry unnecessary. But Chrome’s own documentation concedes an accessibility tree says what a control is, not what it does or under which conditions, so a synchronized button and tool description still doesn’t catch a stale business rule behind either one.