MCP vs WebMCP: Differences and Which to Use (2026)

What MCP is, in one line

MCP (Model Context Protocol) is the open standard used by Claude Fable 5.2, ChatGPT, Gemini CLI, Cursor and many others to connect to services and data. You install a server in your assistant and from then on the assistant can use its tools in any conversation. It's explained in depth in what MCP is and what it's for.

What WebMCP is, in one line

WebMCP is a proposal from the W3C's Web Machine Learning group. It lets a page tell the browser "these are my tools", with their name, description and the data they need. An agent visiting that page can use them directly instead of imitating clicks or reading the HTML blindly.

For developers it's a JavaScript function, document.modelContext.registerTool(), that registers each tool:

document.modelContext.registerTool({
  name: "search_products",
  description: "Search the catalogue by text and maximum price",
  inputSchema: {
    type: "object",
    properties: {
      text: { type: "string" },
      maxPrice: { type: "number" }
    },
    required: ["text"]
  },
  async execute({ text, maxPrice }) {
    return searchCatalogue(text, maxPrice)
  }
})

The tool runs on the page itself, with the code the site already has, so it responds instantly and with the data the user sees.

One example of each

MCP: you connect Context7 to Claude once. From then on, in any chat you can ask "how do I do this in the latest version of this library?" and Claude fetches the current documentation through the server without you opening any website.

WebMCP: you visit asus.com with a browser that supports WebMCP. The site offers seven tools to the agent, such as searching products or checking the FAQs. You ask "show me gaming laptops under $1,500" and the agent uses the site's own search instead of clicking through buttons.

Current status of WebMCP (November 2026)

WebMCP is not stable yet:

• Chrome lists it as "proposed". Developers can try it since Chrome 146 by

turning on an experimental flag.

• There's an origin trial between Chrome 149 and 156, extended to 162, so

websites can test it with real users.

• The specification is a draft that changes every week. It uses

document.modelContext; some older tutorials say navigator.modelContext, which is the previous name.

• Registration through HTML attributes (without JavaScript), mentioned by some

websites, is not part of the specification.

Even so, there are already many websites with WebMCP tools in our WebMCP directory.