> ## Documentation Index
> Fetch the complete documentation index at: https://docs.skybridge.tech/llms.txt
> Use this file to discover all available pages before exploring further.
# Overview
> Every server API, hook, and utility, with host compatibility.
export const Compat = ({alpic = false, chatgpt = false, claude = false, compact = false}) =>
;
Every Skybridge export. Server APIs run in your MCP server and work with any host. [View](/build/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`](/api-reference/mcp-auth-metadata-router) | Serve OAuth metadata for client discovery. |
| [`McpServer`](/api-reference/mcp-server) | The server you register tools and views on. |
| [`optionalBearerAuth`](/api-reference/optional-bearer-auth) | Attach a verified identity when a token is present. |
| [`registerTool`](/api-reference/register-tool) | Register a tool, its schemas, and the view it renders. |
| [`requireBearerAuth`](/api-reference/require-bearer-auth) | Gate a server behind a verified bearer token. |
## Hooks
| Hook | Description | Supported Hosts |
| --------------------------------------------------------------------- | ----------------------------------------------------------------- | --------------------------------------- |
| [`useCallTool`](/api-reference/use-call-tool) | Call server tools from the view and track call state. | |
| [`useDisplayMode`](/api-reference/use-display-mode) | Read and request inline, pip, or fullscreen. | |
| [`useDownload`](/api-reference/use-download) | Save files to the user's device. | |
| [`useFiles`](/api-reference/use-files) | Upload and pick host-managed files. | |
| [`useLayout`](/api-reference/use-layout) | Read theme, max height, and safe-area insets. | |
| [`useOpenExternal`](/api-reference/use-open-external) | Open a URL outside the view iframe. | |
| [`useRegisterViewTool`](/api-reference/use-register-view-tool) | Expose a tool that runs inside the view. | |
| [`useRequestClose`](/api-reference/use-request-close) | Ask the host to dismiss the view. | |
| [`useRequestModal`](/api-reference/use-request-modal) | Open the view as a host modal. | |
| [`useRequestSize`](/api-reference/use-request-size) | Ask the host to resize the view iframe. | |
| [`useSendFollowUpMessage`](/api-reference/use-send-follow-up-message) | Send a follow-up turn to the model. | |
| [`useSetOpenInAppUrl`](/api-reference/use-set-open-in-app-url) | Override the fullscreen open-in-app URL. | |
| [`useToolInfo`](/api-reference/use-tool-info) | Read the tool input, output, and metadata that rendered the view. | |
| [`useUser`](/api-reference/use-user) | Read locale and device capabilities. | |
| [`useViewState`](/api-reference/use-view-state) | Persist UI state on the host across renders. | |
## Utilities
| Utility | Description |
| ---------------------------------------------------- | ----------------------------------------------- |
| [`createStore`](/api-reference/create-store) | A Zustand store synced with host view state. |
| [`data-llm`](/api-reference/data-llm) | Describe on-screen state to the model in words. |
| [`generateHelpers`](/api-reference/generate-helpers) | Generate typed hooks inferred from your server. |
## Types
| Type | Description |
| ---------------------------------------------- | --------------------------------------------------------- |
| [`FileRef`](/api-reference/file-ref) | Reference a host-managed file in a tool schema. |
| [Type Utilities](/api-reference/utility-types) | Pull tool input, output, and name types from your server. |
## Low-level
| Hook | Description |
| ---------------------------------------------------------- | --------------------------------------------------- |
| [`useAppsSdkContext`](/api-reference/use-apps-sdk-context) | Read a raw ChatGPT (Apps SDK) context value by key. |
| [`useMcpAppContext`](/api-reference/use-mcp-app-context) | Read a raw MCP Apps context value by key. |
Scaffold and run your first app
Register the tools these APIs call
How the two runtimes differ and what's unified