Overview

The Built-in Agent is CopilotKit's simplest agent option, i.e what you get "built-in". It connects directly to an LLM with full support for tools, generative UI, shared state, and all CopilotKit features — without requiring an external agent framework.

It supports most popular models from OpenAI, Anthropic, Google, and AI-SDK defined models out of the box

When to use Built-in Agent

• Quick setup — no external agent framework to configure or deploy
• Chat + tools — your use case is primarily conversational with frontend and server tools
• Direct model access — you want to use OpenAI, Anthropic, Google, or AI-SDK models directly

<Callout type="info"> If you need more control over your agent loop, consider using an [agent framework](/#explore-by-ai-backend) instead. </Callout>

Features

<Cards> <Card title="Generative UI" href="/built-in-agent/generative-ui/tool-rendering" description="Render rich React components in the chat." icon={<Sparkles className="text-primary" />} /> <Card title="Frontend Tools" href="/built-in-agent/frontend-tools" description="Let the agent interact with your UI using frontend tools." icon={<Wrench className="text-primary" />} /> <Card title="Server Tools" href="/built-in-agent/server-tools" description="Define backend tools with Zod schemas that the agent can invoke." icon={<Server className="text-primary" />} /> <Card title="MCP Servers" href="/built-in-agent/mcp-servers" description="Connect MCP servers for extended tool capabilities." icon={<Plug className="text-primary" />} /> <Card title="Shared State" href="/built-in-agent/shared-state" description="Bidirectional state sharing between your app and the agent." icon={<ArrowLeftRight className="text-primary" />} /> <Card title="Model Selection" href="/built-in-agent/model-selection" description="Choose from OpenAI, Anthropic, and Google models — or bring your own." icon={<Cpu className="text-primary" />} /> <Card title="Agent Context" href="/built-in-agent/agent-app-context" description="Share app-specific context with the agent automatically." icon={<BookA className="text-primary" />} /> <Card title="Advanced Configuration" href="/built-in-agent/advanced-configuration" description="Fine-tune temperature, tool choice, multi-step calling, and more." icon={<Cog className="text-primary" />} /> <Card title="Custom Agent" href="/built-in-agent/custom-agent" description="Bring your own AI SDK, TanStack AI, or custom LLM backend." icon={<Blocks className="text-primary" />} /> </Cards>

Getting Started

Head to the Quickstart to set up a working Built-in Agent in minutes.