Overview - Skybridge

Every Skybridge export. Server APIs run in your MCP server and work with any host. View hooks run inside the rendered view, where a host that lacks a capability degrades gracefully, either a no-op or a thrown error documented on the hook’s page.

Server

API	Description
`mcpAuthMetadataRouter`	Serve OAuth metadata for client discovery.
`McpServer`	The per-request server your handler registers tools on.
`optionalBearerAuth`	Attach a verified identity when a token is present.
`registerTool`	Register a tool, its schemas, and the view it renders.
`requireBearerAuth`	Gate a server behind a verified bearer token.
`Skybridge`	The app: its config, OAuth, and the handler that registers tools.

Hooks

Hook	Description	Supported Hosts
`useCallTool`	Call server tools from the view and track call state.
`useDisplayMode`	Read and request inline, pip, or fullscreen.
`useDownload`	Save files to the user’s device.
`useFiles`	Upload and pick host-managed files.
`useHost`	Identify which host is rendering the view.
`useOpenExternal`	Open a URL outside the view iframe.
`useRegisterViewTool`	Expose a tool that runs inside the view.
`useRequestClose`	Ask the host to dismiss the view.
`useRequestModal`	Open the view as a host modal.
`useRequestSize`	Ask the host to resize the view iframe.
`useSendFollowUpMessage`	Send a follow-up turn to the model.
`useSetOpenInAppUrl`	Override the fullscreen open-in-app URL.
`useToolInfo`	Read the tool input, output, and metadata that rendered the view.
`useUser`	Read locale, theme, and device capabilities.
`useViewState`	Persist UI state on the host across renders.
`useViewport`	Read the max height and safe-area insets.

Utilities

Utility	Description
`createStore`	A Zustand store synced with host view state.
`data-llm`	Describe on-screen state to the model in words.
`generateHelpers`	Generate typed hooks inferred from your server.

Types

Type	Description
`FileRef`	Reference a host-managed file in a tool schema.
Type Utilities	Pull tool input, output, and name types from your server.

Low-level

Hook	Description
`useAppsSdkContext`	Read a raw ChatGPT (`window.openai`) context value by key.
`useMcpAppContext`	Read a raw MCP Apps context value by key.

Quickstart

Scaffold and run your first app

Build Tools

Register the tools these APIs call

ChatGPT Plugins and MCP Apps

How the two runtimes differ and what’s unified