useApp

Import from bitmcp/react:

import { useApp } from "bitmcp/react";

const { result, callTool, app, isConnected, error } = useApp();

File-based tools generate .bitmcp/views.d.ts so result is inferred from the sibling tool. Pass a generic only when you need to override that.

Fields

Field	Description
`result`	`structuredContent` from the host via `ontoolresult`, or from `callTool`
`callTool(name, args?)`	Calls a backing tool through the host and updates `result`
`app`	Official Apps client instance
`isConnected`	Connection state
`error`	Connection error if any

callTool keeps a stable function identity so poll intervals do not reset every render.

Re-exported from @modelcontextprotocol/ext-apps/react:

import { useMcpApp, useHostStyles } from "bitmcp/react";

Use these only when you need direct access to the official client. The happy path is useApp().

The compiler injects AppShell in the HTML shell. Authors do not render it in view.tsx.