useMcpAppContext

An MCP Apps host (Claude and others) exposes view context that Skybridge’s cross-host hooks read for you. useMcpAppContext is the escape hatch: it reads that context raw, by key, for a protocol-level field the hooks don’t surface. It runs only on MCP Apps hosts, not ChatGPT; the Apps SDK counterpart is useAppsSdkContext.

Example

useUser gives the locale but not the host time zone, so a schedule reads timeZone from the context to render times in the user’s zone.

import { useMcpAppContext } from "skybridge/web";

function Schedule({ events }: { events: Event[] }) {
  const timeZone = useMcpAppContext("timeZone");

  return (
    <ul>
      {events.map((event) => (
        <li key={event.id}>
          {event.start.toLocaleString(undefined, { timeZone })}
        </li>
      ))}
    </ul>
  );
}

Type Parameters

`K`

K extends keyof McpAppContext;

Inferred from key: the literal key you pass fixes the return type to McpAppContext[K].

Parameters

`key`

key: K;

Required. The context key to read and subscribe to. The hook re-renders only when this key changes; to watch several keys, call it once per key.

`options`

options?: Partial<{ appInfo: Implementation }>;

appInfo ({ name, version }) optionally identifies the view to the host. Omit it for a generic default.

Returns

value: McpAppContext[K];

The requested key’s current value, empty until the host provides it: host-context keys are undefined, tool-state keys null. The table lists each key with the cross-host hook that also surfaces it; hosts may send others not listed.

Key	Value	Also via
`theme`	`"light"` or `"dark"`	`useLayout`
`locale`	BCP-47 locale	`useUser`
`timeZone`	IANA time zone	—
`displayMode`	current layout (`inline` / `fullscreen` / `pip`)	`useDisplayMode`
`availableDisplayModes`	layouts the host supports	—
`containerDimensions`	the view’s available size (height and width)	`useLayout`
`userAgent`	raw host user-agent string	—
`platform`	`web` / `desktop` / `mobile`	`useUser`
`deviceCapabilities`	touch and hover support	`useUser`
`safeAreaInsets`	insets to keep clear of host chrome	`useLayout`
`styles`	host theme tokens	—
`toolInfo`	the tool definition that rendered the view	—
`toolInput`	the tool call’s arguments	`useToolInfo`
`toolResult`	the tool’s full MCP result (`structuredContent` model-visible)	`useToolInfo`
`toolCancelled`	set when the host aborts the call	—

useAppsSdkContext

The Apps SDK counterpart for ChatGPT

useToolInfo

Read the tool result across both runtimes

Apps SDK and MCP Apps

What the raw MCP Apps layer is, and how Skybridge unifies it

Server

Auth

Identity Providers

Hooks

Utilities

Types

Low-level

Example

Type Parameters

`K`

Parameters

`key`

`options`

Returns

useAppsSdkContext

useToolInfo

Apps SDK and MCP Apps

​Example

​Type Parameters

​K

​Parameters

​key

​options

​Returns

useAppsSdkContext

useToolInfo

Apps SDK and MCP Apps

Example

Type Parameters

`K`

Parameters

`key`

`options`

Returns