Components as Tools

"""LangGraph agent backing the Tool-Based Generative UI demo.The frontend registers `render_bar_chart` and `render_pie_chart` tools via`useComponent`. CopilotKit's LangGraph middleware injects those tools intothe model request at runtime so the agent can call them."""from langchain.agents import create_agentfrom langchain_openai import ChatOpenAIfrom copilotkit import CopilotKitMiddlewareSYSTEM_PROMPT = """You are a data visualization assistant.When the user asks for a chart, call `render_bar_chart` or `render_pie_chart`with a concise title, short description, and a `data` array of`{label, value}` items. Pick bar for comparisons over a small set ofcategories; pick pie for composition / share-of-whole.Keep chat responses brief -- let the chart do the talking."""graph = create_agent(    model=ChatOpenAI(model="gpt-5.4"),    tools=[],    middleware=[CopilotKitMiddleware()],    system_prompt=SYSTEM_PROMPT,)

What is this?#

Tool-based Generative UI is the simplest form of Generative UI: you register a React component with useComponent, and CopilotKit exposes it to the agent as a tool. When the agent calls the tool, CopilotKit renders your component inline in the chat, passing the tool's arguments straight through as typed props.

Unlike tool rendering, which wraps a real backend tool in a custom UI, tool-based GenUI is the component. There is no handler, no user interaction, no server-side execution. The agent decides when to show it, populates the data, and CopilotKit paints it.

When should I use this?#

Use useComponent when you want to:

• Display rich UI (cards, charts, tables, dashboards) inline in the chat
• Show structured data the agent has derived from its reasoning
• Render previews, status indicators, or visual summaries
• Let the agent present information beyond plain text

For components that need user interaction, see Human-in-the-loop. For operational transparency around a real backend tool, see Tool rendering.

How it works in code#

useComponent takes a name, a Zod schema for its props, and the component to render. The runtime registers it as a frontend tool so the agent can discover it, and Zod validates the LLM's arguments before they reach your component.

import React from "react";import {  CopilotChat,  CopilotKit,  useComponent,} from "@copilotkit/react-core/v2";import { BarChart, barChartPropsSchema } from "./bar-chart";import { PieChart, pieChartPropsSchema } from "./pie-chart";import { useSuggestions } from "./suggestions";function Chat() {  useComponent({    name: "render_bar_chart",    description: "Display a bar chart with labeled numeric values.",    parameters: barChartPropsSchema,    render: BarChart,  });

The component itself is ordinary React: it reads only its props and can stream in as the agent fills the payload. The example above uses Recharts for the bar chart; it doesn't know anything about CopilotKit.