WebMCP Readiness Checker

No WebMCP draft, explainer or README defines a /.well-known/webmcp file. In WebMCP an agent discovers a page's tools by asking the browser for the ones the page registered, with document.modelContext.registerTool() or toolname forms, and the draft's README turned down static manifest files as the way to declare tools. The checker still looks for the file and reports what it finds, but the file earns and costs nothing, and a site without one has nothing to add.

In WebMCP a page declares what an agent can do as tools. Each tool's name, description and input schema (the draft's ModelContextTool) tell the agent what the action is called, what it does and what input it takes. The page hands them to document.modelContext.registerTool(), or puts toolname and tooldescription on a <form> under the declarative explainer. This test passes when the page declares tools either way. An inline <script type="application/webmcp+json"> block is not part of the WebMCP draft or its explainers (the draft's README lists static manifests as an alternative it considered and did not adopt), and no browser reads it, so it is reported as information and scores nothing.

The WebMCP repository's declarative API explainer puts toolname and tooldescription on an existing <form> and toolparamdescription on its controls, so a browser can offer the form to an agent as a tool without any JavaScript. toolautosubmit lets the agent submit the form without the person reviewing it, so leave it off forms that collect personal details or send a request. The declarative API was taken out of the draft spec on 2026-10-08, but Chrome still ships it under the same WebMCP origin trial. data-webmcp-* attributes (data-webmcp-action, data-webmcp-form and the like) appear in no WebMCP draft and no browser reads them: they are reported as information and score nothing.

JavaScript that calls document.modelContext.registerTool({name, description, inputSchema, execute}) once per tool (navigator.modelContext is accepted as an alias). We string-match the page HTML and up to three WebMCP scripts it loads; true presence requires execution, which we don't do. The draft removed the older provideContext() call on 2026-03-05 (pull request 132), so a page that only calls provideContext(), or uses the never-standard window.webmcp names, gets a legacy warning and no points.