This is great. I'm all for agents calling structured tools on sites instead of poking at DOM/screenshots.

But no MCP server today has tools that appear on page load, change with every SPA route, and die when you close the tab. Client support for this would have to be tightly coupled to whatever is controlling the browser.

What they really built is a browser-native tool API borrowing MCP's shape. If calling it "MCP" is what gets web developers to start exposing structured tools for agents, I'll take it.

Yeah, this seems like a weird niche where an agent has to interact with an existing browser session.

That, or they expect that MCP clients should also be running a headless Chrome to detect JS-only MCP endpoints.