Host Model
A Clientless host assembles and renders capabilities. It should not become a second fixed app.
Native MCP App hosts
Section titled “Native MCP App hosts”Native MCP App hosts can load and render MCP Apps directly. Current public MCP Apps documentation lists support across clients including Claude, Claude Desktop, VS Code GitHub Copilot, Goose, Postman, and MCPJam, with the extension matrix tracking client-by-client support.
OpenAI is a primary Clientless target through the ChatGPT Apps SDK, which is built on MCP and runs apps inside ChatGPT.
Support should always be checked against the official host documentation and the MCP extension support matrix before making compatibility claims.
WebHost
Section titled “WebHost”WebHost is the bridge for the ordinary web.
It gives a browser page the host behavior that native MCP App clients already provide:
- connect to capabilities,
- load app resources,
- render interactive surfaces,
- forward actions,
- provide the web registry,
- support SSR or static first paint where useful.
iOS and widgets
Section titled “iOS and widgets”An iOS Clientless shell should be a native host adapter plus a native registry. Widgets can render constrained personal interfaces from the same capability stream, using a smaller catalog when needed.
macOS and Windows
Section titled “macOS and Windows”Desktop shells should behave like surfaces for capabilities. They can own native windows, menus, notifications, storage permissions, and system integrations, while the capability model remains portable across hosts.
Endpoint packages
Section titled “Endpoint packages”Compiling or packaging endpoints into native binaries is an implementation option, not a required part of the model. If tools such as Perryjs can package endpoints cleanly, they can become a deployment lane for local-first or desktop-hosted Clientless capabilities.