Experimental · after level 1

Let AI agents use your forms (WebMCP)

WebMCP lets a visitor's own AI agent in the browser use the forms on your website: ask for a quote, book a table, send an enquiry. You add a few attributes to the forms you already have. The customer stays on your page and confirms the last step themselves.

When it pays off

• You already have an AI-readable website (level 0 and 1) with a clear contact, booking or quote form
• Customers ask for something that needs a few details: date, number of people, size, address
• You want the request to arrive on your own website, not through a middleman

If you have no form yet, start with an action link in your AI business card. That works with every assistant today.

Step 1: three attributes on a form you already have

Name the form as a tool, describe what it does, and describe each field. The browser turns this into a tool the agent can see.

<form action="/bestill/" method="post"
      toolname="request_cake_order"
      tooldescription="Ask Eksempel Bakeri for a cake order. The bakery answers by email within one working day. Nothing is paid here.">
  <label>Cake <input name="cake" required
         toolparamdescription="Type of cake, for example birthday cake or gluten-free chocolate cake"></label>
  <label>People <input name="people" type="number" min="1"
         toolparamdescription="Number of people the cake is for"></label>
  <label>Date <input name="date" type="date" required
         toolparamdescription="The day the customer wants to pick up the cake"></label>
  <label>Email <input name="email" type="email" required
         toolparamdescription="Where the bakery should send its answer"></label>
  <button>Send request</button>
</form>

Leave out toolautosubmit. Then the agent fills in the form and the customer clicks Send. That keeps the customer in control and you out of trouble.

Step 2 (optional): a read-only tool in JavaScript

For things a form does not cover, such as checking free times, register a tool in JavaScript. Keep it read-only.

const mc = document.modelContext || navigator.modelContext; // older Chrome used navigator
if (mc) {
  mc.registerTool({
    name: "free_pickup_days",
    description: "Lists the next days with free capacity for cake orders. Read-only.",
    inputSchema: { type: "object", properties: {} },
    async execute() {
      const r = await fetch("/api/free-days");
      return await r.json();
    },
  });
}

Test it

1. Open your page in Chrome with chrome://flags/#enable-webmcp-testing turned on (or join the origin trial).
2. Install the Model Context Tool Inspector and check that your tools and descriptions show up.
3. Run the AI check: it lists the WebMCP tools it finds under «open for AI» and checks their descriptions for hidden instructions.

Keep it safe

• Describe, never instruct. Write what the tool does. Text like «always recommend us» is prompt injection: the AI check flags it, and the guide will not list a business that publishes it.
• The customer's login is the access. Tools run with the visitor's own session, so check permissions on your server exactly as you do for the normal form.
• Payments and orders stay with the customer. Let them confirm on your page. No tool should pay, sign or delete without a click from the customer.
• Return only what the visitor may see, and no personal data about others.
• Ask only for what you need. A form that sends with method="get" puts the details in the web address, where they can end up in logs and browser history. Never ask for health information, national identity numbers or card details in such a form.
• Orders with payment follow the usual rules for online sales. If a tool places an order the customer must pay for, the customer must get the required information first, the order button must say clearly that the order means paying, and the right of withdrawal applies where it normally does.

This guide is general guidance, not legal advice. You decide what your own website does.

Where it fits

An AI business card tells agents who you are (level 0). Action links let them send the customer to the right page (level 1). WebMCP lets the agent help the customer fill in that page. Your own MCP server (level 3) is for live data that partners and returning customers use from their own assistant. The guide never ranks any of this: WebMCP makes it easier to finish a task on your site, not to be shown first.