Webmcp Agent

Reference

What Is WebMCP

WebMCP is a proposed web standard that lets websites expose structured tools to AI agents through navigator.modelContext, replacing screen-scraping with explicit contracts.

WebMCP is a proposed web standard that lets a website expose actions as tools instead of forcing agents to reverse-engineer the interface. The site describes what can be done. The browser mediates access. The agent calls a tool instead of guessing which pixels to click. The standard lives at navigator.modelContext. The authoritative definition belongs to the W3C WebMCP spec and the Chrome team’s design documents, not to the MCP-B packages. MCP-B exists to help you use that standard today, then extend it when you need browser MCP features beyond the standard.

WebMCP API

Refer to Standard API Document

When to Trigger

Triggered immediately after the AI Agent calls the browser (e.g., via chrome-devtools MCP or similar MCPs/Tools) to enter a page. Once triggered, execute the steps in How to Use immediately.

How to Use

1. Execute listTools script to get the list of all WebMCP tools. If an exception is thrown, skip the subsequent steps.
2. Read the return value of listTools(), which is an array where each element is an object containing three properties: description, name, and inputSchema, corresponding to tool description, tool name, and JSON Schema string for tool input parameters.
3. Decide whether to call these tools as needed. If required, execute the navigator.modelContextTesting.executeTool(tool.name, inputSchema) method, where tool.name is the name of the tool and inputSchema is the JSON Schema string of the tool's input parameters. Note that executeTool returns a Promise<string> which resolves to the execution result.

Refer to Standard API Document