What Is WebMCP (Web Model Context Protocol)?
WebMCP (Web Model Context Protocol) is a new W3C standard jointly developed by Google and Microsoft that lets websites expose structured tools and capabilities directly to AI agents in the browser. It provides a structured "tool contract" instead of agents guessing how to interact with your site.
WebMCP Explained
WebMCP enables a structured communication layer between websites and AI agents. Instead of agents reverse-engineering your UI through screenshots or DOM scraping, WebMCP lets you declare what tools and actions your website offers, complete with defined inputs and outputs.
How WebMCP Works
- Declarative attributes - Add toolname, tooldescription, and toolparamdescription to HTML forms
- Imperative API - Use document.modelContext.provideContext() for dynamic tool registration (the surface that replaced the deprecated navigator.modelContext)
- SDK/polyfill support - Libraries that enable WebMCP in browsers without native support
- Form agent-readiness - Existing well-labeled forms are often close to WebMCP compatibility
WebMCP vs Anthropic's MCP
They are complementary, not competing. Anthropic's MCP is a backend server-to-server protocol that connects AI tools to APIs and databases. Google's WebMCP is a frontend browser protocol that connects AI agents to website UIs. A complete agent stack might use both.
Current Status
WebMCP now ships natively in Chromium (Chrome 146+ and Edge 147+), with tools registered via document.modelContext.provideContext() (the deprecated navigator.modelContext surface was removed in Chrome 150). Adoption is still early, so acting now is a competitive advantage. Glippy's WebMCP checker evaluates your current readiness.
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