What Is WebMCP? Making Web Forms Usable by AI Agents
WebMCP is a proposed web standard, previewing in Chrome, that lets a page describe its actions to AI agents as tools. For an HTML form that means two attributes on the form (toolname and tooldescription) and an optional description per field, from which the browser builds a tool the agent can call.
Without it an agent fills a form the way a person new to the page would: reading labels, guessing what a field wants, and clicking. That works until a label is vague, a field is hidden behind a step, or the page changes.
With it the browser turns the form into a typed tool. The agent sees the field names, types and descriptions, fills the form, and the person confirms before it is sent. A page can tell an agent submission apart (SubmitEvent.agentInvoked) and answer it with structured data through respondWith rather than a thank-you page.
Browsers without WebMCP ignore the attributes, so adding them costs people nothing. The proposal is still changing, so markup generated from a single source is easier to keep current than hand-written attributes.
In WebForms
WebForms adds the WebMCP attributes from your form schema with one script tag, answers agent submissions with JSON, and tags them as browser agent submissions you can route separately.