> ## Documentation Index
> Fetch the complete documentation index at: https://docs.compose.market/llms.txt
> Use this file to discover all available pages before exploring further.

# First Agent Call

> Complete walkthrough: install, authenticate, and stream your first paid agent response.

This guide takes you from zero to your first streamed agent response. You'll install the SDK, create a Compose Key, send a message to a deployed agent, and watch the text arrive in real time.

## 1. Install the SDK

```bash theme={null}
npm install @compose-market/sdk
```

Requires Node.js 20 or later.

## 2. Initialize the client

```typescript theme={null}
import ComposeSDK from "@compose-market/sdk";

const sdk = new ComposeSDK({
  userAddress: "0xYourWalletAddress",
  chainId: 43113,
});
```

`userAddress` is your EVM wallet address. `chainId` is the chain you'll settle payments on — `43113` is Avalanche Fuji testnet.

## 3. Create a Compose Key

A Compose Key is a bearer token that handles payment server-side. You create it once and the SDK stores and reuses it automatically.

```typescript theme={null}
const { token } = await sdk.keys.create({
  userAddress: "0xYourWalletAddress",
  chainId: 43113,
});

// The SDK now attaches this token to every request.
// In a browser it persists in localStorage; in Node.js it stays in memory.
```

## 4. Stream an agent response

Pick any deployed agent and send a message. The response comes back as an SSE stream of typed events.

```typescript theme={null}
const agentWallet = "0xa7abfd271130c3ee5c8f8862a123f3697e75af0d";

const stream = sdk.agent.stream({
  agentWallet,
  message: "Hey, what do you do?",
  threadId: "my-first-chat",
});
```

## 5. Handle events

Iterate the stream and handle the events you care about. The most common is `text-delta` — a fragment of the agent's reply.

```typescript theme={null}
for await (const event of stream) {
  switch (event.type) {
    case "text-delta":
      process.stdout.write(event.delta);
      break;
    case "tool_start":
      console.log(`\n[Tool: ${event.toolName}]`);
      break;
    case "tool_end":
      console.log(`[Done: ${event.toolName}]`);
      break;
    case "done":
      console.log(`\n\nTokens: ${event.usage.total_tokens}`);
      break;
    case "error":
      console.error(`Error: ${event.error}`);
      break;
  }
}
```

## 6. Get the final result

After the stream ends, the iterator resolves with a final result containing the full text, tool call summaries, and the payment receipt.

```typescript theme={null}
const stream = sdk.agent.stream({
  agentWallet,
  message: "Hey, what do you do?",
  threadId: "my-first-chat",
});

for await (const event of stream) {
  if (event.type === "text-delta") process.stdout.write(event.delta);
}

const final = await stream.next();
console.log(final.value.receipt);
console.log(final.value.budget);
```

## The complete script

```typescript theme={null}
import ComposeSDK from "@compose-market/sdk";

const sdk = new ComposeSDK({
  userAddress: "0xYourWalletAddress",
  chainId: 43113,
});

await sdk.keys.create({
  userAddress: "0xYourWalletAddress",
  chainId: 43113,
});

const stream = sdk.agent.stream({
  agentWallet: "0xa7abfd271130c3ee5c8f8862a123f3697e75af0d",
  message: "Hey, what do you do?",
  threadId: "my-first-chat",
});

for await (const event of stream) {
  if (event.type === "text-delta") process.stdout.write(event.delta);
  if (event.type === "done") console.log(`\n\nTokens: ${event.usage.total_tokens}`);
}
```

That's a complete paid agent call. The SDK handled authentication, payment negotiation, SSE parsing, and receipt extraction — you only wrote the event loop.

## Next

* [Paid Streaming with x402](/sdk/guides/paid-streaming) — raw wallet signing, no Compose Key
* [Stream Protocol](/sdk/streaming/protocol) — every event type
* [Slash Commands](/sdk/commands/overview) — control agents with `/plan`, `/goal`, `/mode`