# AssistantRuntime
URL: /docs/api-reference/runtimes/assistant-runtime

Root runtime for managing threads, tool UIs, and assistant state.

***

title: AssistantRuntime
description: Root runtime for managing threads, tool UIs, and assistant state.
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import { ParametersTable } from "@/components/docs/tables/ParametersTable";
import { AssistantRuntime, AssistantToolUIsState } from "@/generated/typeDocs";

The `AssistantRuntime` is the root runtime of the application.

### `useAssistantRuntime`

```tsx
import { useAssistantRuntime } from "@assistant-ui/react";

const runtime = useAssistantRuntime();
```

<ParametersTable {...AssistantRuntime} />

### Tool UI Registry

The tool UI registry is part of the assistant runtime. It allows you to display custom UI for tool calls, enabling generative UI.