---
description: Build a streaming AI chat agent with tools using Workers AI — no API keys required.
title: Chat agent
image: https://developers.cloudflare.com/og-docs.png
---

[Skip to content](#main-content)

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/agents/llms.txt  
> Use this file to discover all available pages before exploring further.

# Chat agent

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/examples/chat-agent/index.md)|[Agent setup](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agent-setup/)

Build a chat agent that streams AI responses, calls server-side tools, executes client-side tools in the browser, and asks for user approval before sensitive actions.

**What you will build:** A chat agent powered by Workers AI with three tool types — automatic, client-side, and approval-gated.

**Time:** \~15 minutes

This tutorial starts from a minimal Hello World Worker so you can see each moving part. If you want a complete starter app with the same core pieces already wired together, start with the [quick start](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/getting-started/quick-start/) and then return here to understand how the chat pieces fit together.

**Prerequisites:**

* Node.js 18+
* A Cloudflare account (free tier works)

## 1\. Create the project

```sh
npm create cloudflare@latest chat-agent
```

Select **"Hello World" Worker** when prompted. Then install the dependencies:

```sh
cd chat-agent
npm install agents @cloudflare/ai-chat ai workers-ai-provider zod
```

## 2\. Configure Wrangler

Replace your `wrangler.jsonc` with:

```jsonc
{
	"name": "chat-agent",
	"main": "src/server.ts",
	// Set this to today's date
	"compatibility_date": "2026-08-24",
	"compatibility_flags": ["nodejs_compat"],
	"ai": { "binding": "AI" },
	"durable_objects": {
		"bindings": [{ "name": "ChatAgent", "class_name": "ChatAgent" }],
	},
	"migrations": [{ "tag": "v1", "new_sqlite_classes": ["ChatAgent"] }],
}
```

```toml
name = "chat-agent"
main = "src/server.ts"
# Set this to today's date
compatibility_date = "2026-08-24"
compatibility_flags = [ "nodejs_compat" ]

[ai]
binding = "AI"

[[durable_objects.bindings]]
name = "ChatAgent"
class_name = "ChatAgent"

[[migrations]]
tag = "v1"
new_sqlite_classes = [ "ChatAgent" ]
```

Key settings:

* `ai` binds Workers AI — no API key needed
* `durable_objects` registers your chat agent class
* `new_sqlite_classes` enables SQLite storage for message persistence

## 3\. Write the server

Create `src/server.ts`. This is where your agent lives:

```js
import { AIChatAgent } from "@cloudflare/ai-chat";
import { routeAgentRequest } from "agents";
import { createWorkersAI } from "workers-ai-provider";
import {
	streamText,
	convertToModelMessages,
	pruneMessages,
	tool,
	stepCountIs,
} from "ai";
import { z } from "zod";

export class ChatAgent extends AIChatAgent {
	async onChatMessage() {
		const workersai = createWorkersAI({ binding: this.env.AI });

		const result = streamText({
			model: workersai("@cf/meta/llama-4-scout-17b-16e-instruct"),
			system:
				"You are a helpful assistant. You can check the weather, " +
				"get the user's timezone, and run calculations.",
			messages: pruneMessages({
				messages: await convertToModelMessages(this.messages),
				toolCalls: "before-last-2-messages",
			}),
			tools: {
				// Server-side tool: runs automatically on the server
				getWeather: tool({
					description: "Get the current weather for a city",
					inputSchema: z.object({
						city: z.string().describe("City name"),
					}),
					execute: async ({ city }) => {
						// Replace with a real weather API in production
						const conditions = ["sunny", "cloudy", "rainy"];
						const temp = Math.floor(Math.random() * 30) + 5;
						return {
							city,
							temperature: temp,
							condition:
								conditions[Math.floor(Math.random() * conditions.length)],
						};
					},
				}),

				// Client-side tool: no execute function — the browser handles it
				getUserTimezone: tool({
					description: "Get the user's timezone from their browser",
					inputSchema: z.object({}),
				}),

				// Approval tool: requires user confirmation before executing
				calculate: tool({
					description:
						"Perform a math calculation with two numbers. " +
						"Requires user approval for large numbers.",
					inputSchema: z.object({
						a: z.coerce.number().describe("First number"),
						b: z.coerce.number().describe("Second number"),
						operator: z
							.enum(["+", "-", "*", "/", "%"])
							.describe("Arithmetic operator"),
					}),
					needsApproval: async ({ a, b }) =>
						Math.abs(a) > 1000 || Math.abs(b) > 1000,
					execute: async ({ a, b, operator }) => {
						const ops = {
							"+": (x, y) => x + y,
							"-": (x, y) => x - y,
							"*": (x, y) => x * y,
							"/": (x, y) => x / y,
							"%": (x, y) => x % y,
						};
						if (operator === "/" && b === 0) {
							return { error: "Division by zero" };
						}
						return {
							expression: `${a} ${operator} ${b}`,
							result: ops[operator](a, b),
						};
					},
				}),
			},
			stopWhen: stepCountIs(5),
		});

		return result.toUIMessageStreamResponse();
	}
}

export default {
	async fetch(request, env) {
		return (
			(await routeAgentRequest(request, env)) ||
			new Response("Not found", { status: 404 })
		);
	},
};
```

```ts
import { AIChatAgent } from "@cloudflare/ai-chat";
import { routeAgentRequest } from "agents";
import { createWorkersAI } from "workers-ai-provider";
import {
	streamText,
	convertToModelMessages,
	pruneMessages,
	tool,
	stepCountIs,
} from "ai";
import { z } from "zod";

export class ChatAgent extends AIChatAgent {
	async onChatMessage() {
		const workersai = createWorkersAI({ binding: this.env.AI });

		const result = streamText({
			model: workersai("@cf/meta/llama-4-scout-17b-16e-instruct"),
			system:
				"You are a helpful assistant. You can check the weather, " +
				"get the user's timezone, and run calculations.",
			messages: pruneMessages({
				messages: await convertToModelMessages(this.messages),
				toolCalls: "before-last-2-messages",
			}),
			tools: {
				// Server-side tool: runs automatically on the server
				getWeather: tool({
					description: "Get the current weather for a city",
					inputSchema: z.object({
						city: z.string().describe("City name"),
					}),
					execute: async ({ city }) => {
						// Replace with a real weather API in production
						const conditions = ["sunny", "cloudy", "rainy"];
						const temp = Math.floor(Math.random() * 30) + 5;
						return {
							city,
							temperature: temp,
							condition:
								conditions[Math.floor(Math.random() * conditions.length)],
						};
					},
				}),

				// Client-side tool: no execute function — the browser handles it
				getUserTimezone: tool({
					description: "Get the user's timezone from their browser",
					inputSchema: z.object({}),
				}),

				// Approval tool: requires user confirmation before executing
				calculate: tool({
					description:
						"Perform a math calculation with two numbers. " +
						"Requires user approval for large numbers.",
					inputSchema: z.object({
						a: z.coerce.number().describe("First number"),
						b: z.coerce.number().describe("Second number"),
						operator: z
							.enum(["+", "-", "*", "/", "%"])
							.describe("Arithmetic operator"),
					}),
					needsApproval: async ({ a, b }) =>
						Math.abs(a) > 1000 || Math.abs(b) > 1000,
					execute: async ({ a, b, operator }) => {
						const ops: Record<string, (x: number, y: number) => number> = {
							"+": (x, y) => x + y,
							"-": (x, y) => x - y,
							"*": (x, y) => x * y,
							"/": (x, y) => x / y,
							"%": (x, y) => x % y,
						};
						if (operator === "/" && b === 0) {
							return { error: "Division by zero" };
						}
						return {
							expression: `${a} ${operator} ${b}`,
							result: ops[operator](a, b),
						};
					},
				}),
			},
			stopWhen: stepCountIs(5),
		});

		return result.toUIMessageStreamResponse();
	}
}

export default {
	async fetch(request: Request, env: Env) {
		return (
			(await routeAgentRequest(request, env)) ||
			new Response("Not found", { status: 404 })
		);
	},
} satisfies ExportedHandler<Env>;
```

### What each tool type does

| Tool            | execute? | needsApproval?      | Behavior                                        |
| --------------- | -------- | ------------------- | ----------------------------------------------- |
| getWeather      | Yes      | No                  | Runs on the server automatically                |
| getUserTimezone | No       | No                  | Sent to the client; browser provides the result |
| calculate       | Yes      | Yes (large numbers) | Pauses for user approval, then runs on server   |

## 4\. Write the client

Create `src/client.tsx`:

```js
import { useAgent } from "agents/react";
import { useAgentChat, getToolApproval } from "@cloudflare/ai-chat/react";

function Chat() {
	const agent = useAgent({ agent: "ChatAgent" });

	const {
		messages,
		sendMessage,
		clearHistory,
		addToolApprovalResponse,
		status,
	} = useAgentChat({
		agent,
		// Handle client-side tools (tools with no server execute function)
		onToolCall: async ({ toolCall, addToolOutput }) => {
			if (toolCall.toolName === "getUserTimezone") {
				addToolOutput({
					toolCallId: toolCall.toolCallId,
					output: {
						timezone: Intl.DateTimeFormat().resolvedOptions().timeZone,
						localTime: new Date().toLocaleTimeString(),
					},
				});
			}
		},
	});

	return (
		<div>
			<div>
				{messages.map((msg) => (
					<div key={msg.id}>
						<strong>{msg.role}:</strong>
						{msg.parts.map((part, i) => {
							if (part.type === "text") {
								return <span key={i}>{part.text}</span>;
							}

							// Render approval UI for tools that need confirmation
							if (part.state === "approval-requested") {
								const approval = getToolApproval(part);
								if (!approval) return null;
								return (
									<div key={part.toolCallId}>
										<p>
											Approve <strong>{part.toolName}</strong>?
										</p>
										<pre>{JSON.stringify(part.input, null, 2)}</pre>
										<button
											onClick={() =>
												addToolApprovalResponse({
													id: approval.id,
													approved: true,
												})
											}
										>
											Approve
										</button>
										<button
											onClick={() =>
												addToolApprovalResponse({
													id: approval.id,
													approved: false,
												})
											}
										>
											Reject
										</button>
									</div>
								);
							}

							// Show completed tool results
							if (part.state === "output-available") {
								return (
									<details key={part.toolCallId}>
										<summary>{part.toolName} result</summary>
										<pre>{JSON.stringify(part.output, null, 2)}</pre>
									</details>
								);
							}

							return null;
						})}
					</div>
				))}
			</div>

			<form
				onSubmit={(e) => {
					e.preventDefault();
					const input = e.currentTarget.elements.namedItem("message");
					sendMessage({ text: input.value });
					input.value = "";
				}}
			>
				<input name="message" placeholder="Try: What's the weather in Paris?" />
				<button type="submit" disabled={status === "streaming"}>
					Send
				</button>
			</form>

			<button onClick={clearHistory}>Clear history</button>
		</div>
	);
}

export default function App() {
	return <Chat />;
}
```

```ts
import { useAgent } from "agents/react";
import { useAgentChat, getToolApproval } from "@cloudflare/ai-chat/react";

function Chat() {
	const agent = useAgent({ agent: "ChatAgent" });

	const { messages, sendMessage, clearHistory, addToolApprovalResponse, status } =
		useAgentChat({
			agent,
			// Handle client-side tools (tools with no server execute function)
			onToolCall: async ({ toolCall, addToolOutput }) => {
				if (toolCall.toolName === "getUserTimezone") {
					addToolOutput({
						toolCallId: toolCall.toolCallId,
						output: {
							timezone: Intl.DateTimeFormat().resolvedOptions().timeZone,
							localTime: new Date().toLocaleTimeString(),
						},
					});
				}
			},
		});

	return (
		<div>
			<div>
				{messages.map((msg) => (
					<div key={msg.id}>
						<strong>{msg.role}:</strong>
						{msg.parts.map((part, i) => {
							if (part.type === "text") {
								return <span key={i}>{part.text}</span>;
							}

							// Render approval UI for tools that need confirmation
							if (part.state === "approval-requested") {
								const approval = getToolApproval(part);
								if (!approval) return null;
								return (
									<div key={part.toolCallId}>
										<p>
											Approve <strong>{part.toolName}</strong>?
										</p>
										<pre>{JSON.stringify(part.input, null, 2)}</pre>
										<button
											onClick={() =>
												addToolApprovalResponse({
													id: approval.id,
													approved: true,
												})
											}
										>
											Approve
										</button>
										<button
											onClick={() =>
												addToolApprovalResponse({
													id: approval.id,
													approved: false,
												})
											}
										>
											Reject
										</button>
									</div>
								);
							}

							// Show completed tool results
							if (part.state === "output-available") {
								return (
									<details key={part.toolCallId}>
										<summary>{part.toolName} result</summary>
										<pre>{JSON.stringify(part.output, null, 2)}</pre>
									</details>
								);
							}

							return null;
						})}
					</div>
				))}
			</div>

			<form
				onSubmit={(e) => {
					e.preventDefault();
					const input = e.currentTarget.elements.namedItem(
						"message",
					) as HTMLInputElement;
					sendMessage({ text: input.value });
					input.value = "";
				}}
			>
				<input name="message" placeholder="Try: What's the weather in Paris?" />
				<button type="submit" disabled={status === "streaming"}>
					Send
				</button>
			</form>

			<button onClick={clearHistory}>Clear history</button>
		</div>
	);
}

export default function App() {
	return <Chat />;
}
```

### Key client concepts

* **`useAgent`** connects to your `ChatAgent` over WebSocket
* **`useAgentChat`** manages the chat lifecycle (messages, streaming, tools)
* **`onToolCall`** handles client-side tools — when the LLM calls `getUserTimezone`, the browser provides the result and the conversation auto-continues
* **`addToolApprovalResponse`** approves or rejects tools that have `needsApproval`
* Messages, streaming, and resumption are all handled automatically

## 5\. Run locally

Generate types and start the dev server:

```sh
npx wrangler types
npm run dev
```

Try these prompts:

* **"What is the weather in Tokyo?"** — calls the server-side `getWeather` tool
* **"What timezone am I in?"** — calls the client-side `getUserTimezone` tool (the browser provides the answer)
* **"What is 5000 times 3?"** — triggers the approval UI before executing (numbers over 1000)

## 6\. Deploy

```sh
npx wrangler deploy
```

Your agent is now live on Cloudflare's global network. Messages persist in SQLite, streams resume on disconnect, and the agent hibernates when idle to save resources.

## What you built

Your chat agent has:

* **Streaming AI responses** via Workers AI (no API keys)
* **Message persistence** in SQLite — conversations survive restarts
* **Server-side tools** that execute automatically
* **Client-side tools** that run in the browser and feed results back to the LLM
* **Human-in-the-loop approval** for sensitive operations
* **Resumable streaming** — if a client disconnects mid-stream, it picks up where it left off

## Next steps

### [Chat agents API reference](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/communication-channels/chat/chat-agents/)

Full reference for AIChatAgent and useAgentChat — providers, storage, advanced patterns.

### [Store and sync state](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/runtime/lifecycle/state/)

Add real-time state beyond chat messages.

### [Callable methods](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/runtime/lifecycle/callable-methods/)

Expose agent methods as typed RPC for your client.

### [Human-in-the-loop](https://mchen-ai-models-sync.previews.developers.cloudflare.com/agents/concepts/agentic-patterns/human-in-the-loop/)

Deeper patterns for approval flows and manual intervention.

Was this helpful?

YesNo

## On this page

[![](https://mchen-ai-models-sync.previews.developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://mchen-ai-models-sync.previews.developers.cloudflare.com/)

```json
{"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/agents/examples/chat-agent/#page","headline":"Chat agent · Cloudflare Agents docs","description":"Build a streaming AI chat agent with tools using Workers AI — no API keys required.","url":"https://developers.cloudflare.com/agents/examples/chat-agent/","inLanguage":"en","image":"https://developers.cloudflare.com/og-docs.png","dateModified":"2026-08-24","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. Build, secure, and scale without managing infrastructure","url":"https://www.cloudflare.com/","sameAs":["https://github.com/cloudflare","https://www.linkedin.com/company/cloudflare","https://x.com/cloudflare"],"logo":{"@type":"ImageObject","url":"https://developers.cloudflare.com/logo.svg"},"address":{"@type":"PostalAddress","streetAddress":"101 Townsend St","addressLocality":"San Francisco","addressRegion":"CA","postalCode":"94107","addressCountry":"US"},"contactPoint":[{"@type":"ContactPoint","contactType":"Customer Support","url":"https://support.cloudflare.com/","availableLanguage":["English"]},{"@type":"ContactPoint","contactType":"Sales","url":"https://www.cloudflare.com/contact/","availableLanguage":["English"]}]},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}}
```