WebMCP Tool Registration (Imperative API)

Before writing code

Fetch live docs:

1. Fetch https://webmachinelearning.github.io/webmcp/ for the latest registerTool method signature and parameters
2. Web-search webmcp navigator.modelContext registerTool specification for the full API reference
3. Web-search site:developer.chrome.com webmcp registerTool for Chrome-specific guidance
4. Web-search site:github.com mcp-b registerTool for polyfill-compatible registration patterns

Conceptual Architecture

What registerTool Does

navigator.modelContext.registerTool() is the core imperative method for exposing a tool to AI agents. Each registered tool becomes discoverable and invocable by any agent integrated with the browser.

Tool Definition Object

A tool object passed to registerTool() has these fields: