Concepts
What Is WebMCP?
The proposed API, why it exists, and how it relates to AI agents in the browser.
WebMCP vs MCP
How WebMCP relates to the server-side Model Context Protocol.
Native vs Polyfill vs Global
Three runtime strategies and when each one applies.
Strict Core vs MCP-B Extensions
Where the specification ends and the MCP-B extension layer begins.
Architecture
Runtime Layering
How native APIs, the polyfill, and BrowserMcpServer stack on top of each other.
Transports and Bridges
How tools cross tab, iframe, extension, and desktop boundaries.
Tool Lifecycle and Context Replacement
Registration, discovery, context replacement, and why ordering matters.
Design
Tool Design
Principles for naming, schemas, composability, and failure handling.
Security and Human-in-the-Loop
The safety model, user presence, and browser-mediated trust.
Spec Status and Limitations
Where the specification stands and what is still changing.