useHost

The same view runs inside every host: Claude, Cursor, Goose, and others. useHost reports which one, taken from the MCP Apps ui/initialize handshake, so the view can adapt copy, shortcuts, or layout to the host it’s rendering in. It runs only on MCP Apps hosts; the name is normalized to a Host slug when recognized, otherwise passed through as a raw string.

Example

An empty state suggests the next action using the wording that fits the host.

import { useHost } from "skybridge/web";

function EmptyState() {
  const { name } = useHost();
  const hint =
    name === "claude"
      ? "Ask Claude to add your first item."
      : "Send a message to add your first item.";

  return <p className="empty">{hint}</p>;
}

Returns

`name`

name: Host | (string & {}) | undefined;

The host’s reported name. It resolves to a Host slug for recognized hosts, a raw string for hosts not yet mapped, and undefined until the handshake completes — the view renders first and re-renders once the host responds. The (string & {}) keeps the known slugs in autocomplete while still accepting any string.

`version`

version: string | undefined;

The host’s version string, or undefined until the handshake completes.

`capabilities`

capabilities: McpUiHostCapabilities | undefined;

The host’s MCP Apps capabilities from the handshake, such as downloadFile, openLinks, message or experimental. undefined until the handshake completes.

`openaiCapabilities`

openaiCapabilities: {
  resource: boolean;
  modelContext: boolean;
  message: boolean;
  files: boolean;
};

This is an OpenAI MCP extension, not part of MCP or MCP Apps. Only ChatGPT supports it, and other hosts ignore it.

Which OpenAI MCP extensions the host supports. A flag is true only when the host advertises experimental["openai/<name>"], so every flag is false before the handshake and on hosts other than ChatGPT.

Flag	Extension
`resource`	Read, subscribe to and write the file opened through a file entrypoint. See `useFileResource`.
`modelContext`	Titles, thumbnails and background content in model context.
`message`	Messages sent to a new conversation, and titled items in a message. See `useSendFollowUpMessage`.
`files`	Open a local file in ChatGPT. See `useOpenFile`.

const { openaiCapabilities } = useHost();

return openaiCapabilities.files ? <OpenInChatGPTButton /> : null;

Host

The recognized hosts, as normalized slugs. An unrecognized host surfaces its raw reported name instead.

type Host =
  | "chatgpt"
  | "claude"
  | "cursor"
  | "goose"
  | "mistral-vibe"
  | "alpic";

Slug	Reported `hostInfo.name`
`chatgpt`	`chatgpt`
`claude`	`Claude`
`cursor`	`Cursor`
`goose`	`MCP-UI Host`
`mistral-vibe`	`Le Chat`
`alpic`	`alpic-playground`

useUser

Read the host’s locale and device capabilities

useMcpAppContext

Read a raw MCP Apps context value by key

Design for the Host

Adapt the view to the host it runs in

Server

Auth

Identity Providers

Hooks

Utilities

Types

Low-level

Example

Returns

`name`

`version`

`capabilities`

`openaiCapabilities`

Host

useUser

useMcpAppContext

Design for the Host

​Example

​Returns

​name

​version

​capabilities

​openaiCapabilities

​Host

useUser

useMcpAppContext

Design for the Host

Example

Returns

`name`

`version`

`capabilities`

`openaiCapabilities`

Host