What is WebMCP?

1.What is WebMCP?

WebMCP lets a page describe its own actions to an agent running in the browser. A travel site could register a 'search flights' tool; a SaaS pricing page could register a 'compare plans' tool. The agent calls the tool with structured input instead of guessing which buttons to press, and the call runs in the page with the user's existing session.

Authors listed on the proposal include engineers from Microsoft (Brandon Walderman, Leo Lee, Andrew Nolan) and Google (David Bokan, Khushal Sagar, Hannah Van Opstal).

2.What are the imperative and declarative forms?

• Imperative: JavaScript registers a tool with a name, description, input schema and a function to run. This is the form most of the current explainer covers.
• Declarative: tools are synthesised from existing HTML <form> elements, described in a separate declarative API explainer.

document.modelContext.registerTool({
  name: "compare_plans",
  description: "Compare subscription plans by monthly price and seat limit.",
  inputSchema: {
    type: "object",
    properties: { seats: { type: "number" } },
    required: ["seats"]
  },
  async execute({ seats }) {
    return await fetch(`/api/plans?seats=${seats}`).then(r => r.json());
  }
});

The explainer also describes getTools(), executeTool() and a toolchange event for pages whose tools change. TypeScript types are published in the webmcp-types npm package.

3.How is WebMCP different from MCP?

MCP connects an agent to a server. WebMCP connects an agent to the page it is already on. The first suits API-backed tasks from any agent; the second suits in-browser tasks that depend on the page state and the user's session. Full comparison: MCP and WebMCP.

4.What does WebMCP not do?

• It does not help agents that never load your page in a browser, such as API-only agents.
• It is not a finished web standard. It is a Community Group proposal with open issues.
• It does not replace readable content. An agent still has to understand the page.

5.How do you check WebMCP tools?

1. Open the page in a browser with a WebMCP inspector. nekuda publishes a WebMCP Chrome extension for inspecting and testing tools.
2. Confirm each tool has a clear name, description and input schema.
3. ora.ai's WebMCP audit loads a site in a real browser and scores the tools it exposes out of 100 across shared experience, tool selection, tool quality and trust; a local run is npx ax webmcp-audit http://localhost:3000.
4. webmcp.com lists sites whose WebMCP tools it has verified as live.

6.Where does it sit in the readiness stack?

Layer 3, Act: it is the in-browser route for agents to complete tasks.

Frequently asked questions