assistant-ui Tools

Always consult assistant-ui.com/llms.txt for latest API.

Tools let LLMs trigger actions with custom UI rendering.

References ./references/make-tool.md -- makeAssistantTool/useAssistantTool ./references/tool-ui.md -- makeAssistantToolUI rendering ./references/human-in-loop.md -- Confirmation patterns Tool Types Where does the tool execute? ├─ Backend (LLM calls API) → AI SDK tool() │ └─ Want custom UI? → makeAssistantToolUI └─ Frontend (browser-only) → makeAssistantTool └─ Want custom UI? → makeAssistantToolUI

Backend Tool with UI // Backend (app/api/chat/route.ts) import { tool, stepCountIs } from "ai"; import { z } from "zod";

const tools = { get_weather: tool({ description: "Get weather for a city", inputSchema: z.object({ city: z.string() }), execute: async ({ city }) => ({ temp: 22, city }), }), };

const result = streamText({ model: openai("gpt-4o"), messages, tools, stopWhen: stepCountIs(5), });

// Frontend import { makeAssistantToolUI } from "@assistant-ui/react";

const WeatherToolUI = makeAssistantToolUI({ toolName: "get_weather", render: ({ args, result, status }) => { if (status === "running") return

Loading weather...

; return

{result?.city}: {result?.temp}°C

; }, });

// Register in app

Frontend-Only Tool import { makeAssistantTool } from "@assistant-ui/react"; import { z } from "zod";

API Reference // makeAssistantToolUI props interface ToolUIProps { toolCallId: string; toolName: string; args: Record; argsText: string; result?: unknown; status: "running" | "complete" | "incomplete" | "requires-action"; submitResult: (result: unknown) => void; // For interactive tools }

Human-in-the-Loop const DeleteToolUI = makeAssistantToolUI({ toolName: "delete_file", render: ({ args, status, submitResult }) => { if (status === "requires-action") { return (

Delete {args.path}?

); } return

File deleted

; }, });

Common Gotchas

Tool UI not rendering

toolName must match exactly (case-sensitive) Register UI inside AssistantRuntimeProvider

Tool not being called

Check tool description is clear Use stopWhen: stepCountIs(n) to allow multi-step

Result not showing

Tool must return a value Check status === "complete" before accessing result

安装