This guide will cover how you can get started building messaging agents for Base App, using XMTP, a decentralized messaging protocol. Discover a fast, easy way to build and get distribution in Base App.
  • Why agents?
  • Getting started with XMTP
  • Getting featured in Base App

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Why agents?

Messaging is the largest use-case in the world, but it’s more than just conversations—it’s a secure, programmable channel for financial and social innovation. When combined with the onchain capabilities of Base App, builders have a new surface area to build 10X better messaging experiences not currently possible on legacy platforms like WhatsApp or Messenger. Real Examples: • Smart Payment Assistant: Text “split dinner $200 4 ways” and everyone gets paid instantly with sub-cent fees, no app switching or Venmo delays. • AI Trading Companion: Message “buy 100ETHwhenithits100 ETH when it hits 3,000” and your agent executes trades 24/7 while you sleep. • Travel Planning Agent: “Book flight LAX to NYC under $300” and get instant booking with crypto payments, all in your group chat • Base App & XMTP are combining AI, crypto, and mini apps with secure messaging – to unlock use-cases never before possible. Secure group chats & DMs are the new surface area for developers.

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Getting started

This guide will walk you through creating, testing, and deploying your first XMTP messaging agent. By the end, you’ll have a fully functional agent that can send and receive messages on the XMTP messaging network. Prerequisites
• Node.js (v20 or higher)
• Git
• A code editor
• Basic knowledge of JavaScript/TypeScript Resources STEP 1: SET UP YOUR DEVELOPMENT ENVIRONMENT Clone the XMTP Agent Examples Repository: 
git clone https://github.com/ephemeraHQ/xmtp-agent-examples.git
cd xmtp-agent-examples
STEP 2: INSTALL DEPENDENCIES Install all required packages: 
npm install
STEP 3: GENERATE KEYS FOR YOUR AGENT Run the key generation script to create your agent’s wallet: 
npm run gen:keys
This creates a .env file with: 
WALLET_KEY=0x... # Your agent's private key
ENCRYPTION_KEY=... # Encryption key for local database
XMTP_ENV=dev # Environment (local, dev, production)
STEP 4: WRITE YOUR AGENT LOGIC Create a basic agent that responds to messages: 
// import the xmtp sdk
import { Client, type XmtpEnv, type Signer } from "@xmtp/node-sdk";

// encryption key, must be consistent across runs
const encryptionKey: Uint8Array = ...;
const signer: Signer = ...;
const env: XmtpEnv = "dev";

// create the client
const client = await Client.create(signer, {encryptionKey, env });
// sync the client to get the latest messages
await client.conversations.sync();

// listen to all messages
const stream = await client.conversations.streamAllMessages();
for await (const message of  stream) {
  // ignore messages from the agent
  if (message?.senderInboxId === client.inboxId ) continue;
  // get the conversation by id
  const conversation = await client.conversations.getConversationById(message.conversationId);
  // send a message from the agent
  await conversation.send("gm");
}
Then run your agent: 
npm run dev

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Getting the address of a user

Each user has a unique inboxId for retrieving their associated addresses (identifiers). One inboxId can have multiple identifiers like passkeys or EVM wallet addresses. 
const inboxState = await client.preferences.inboxStateFromInboxIds([
  message.senderInboxId,
]);
const addressFromInboxId = inboxState[0].identifiers[0].identifier;
You can also explore example implementations in the /examples folder, including: STEP 5: TEST YOUR AGENT Development Testing
  1. Start your agent:
npm run dev
  1. Test on xmtp.chat:
    • Go to https://xmtp.chat
    • Connect your personal wallet
    • Switch to Dev environment in settings
    • Start a new conversation with your agent’s public address (from .env)
    • Send a test message and verify the agent responds
Production Testing
  1. Update environment:
XMTP_ENV=production
  1. Test on Base App:
    • Open Base App mobile app
    • Go to messaging
    • Start conversation with your agent’s address
    • Verify functionality
STEP 6: GET A BASENAME FOR YOUR AGENT Give your agent a human-readable name: 1. Import agent wallet to Base App extension:
• Install Base App browser extension
• Import using your agent’s private key 2. Purchase a basename:
• Visit https://base.org/names
• Connect your agent’s wallet
• Search and purchase your desired basename (e.g., myagent.base.eth)
• Set as primary name 3. Verify setup:
• Your agent can now be reached via the basename instead of the long address
• Users can message myagent.base.eth instead of 0x123… STEP 7: DEPLOY YOUR AGENT Option 1: Railway (Recommended) • Visit https://railway.app
• Connect your GitHub repository
• Add environment variables in Railway dashboard:
- XMTP_ENV=production
- WALLET_KEY=your_agent_private_key
- ENCRYPTION_KEY=your_agent_encryption_key • Deploy and monitor logs Option 2: Other Platforms
Heroku, Vercel, or any Node.js hosting platform:
• Ensure your package.json has the correct start script
• Set environment variables in your hosting platform
• Deploy your repository STEP 8: MONITOR AND MAINTAIN Best Practices
  1. Logging: Add comprehensive logging to track agent activity
  2. Error Handling: Implement try-catch blocks for network issues
  3. Rate Limiting: Respect XMTP rate limits in your agent logic
  4. Security: Never expose private keys; use environment variables
Monitoring Add to your agent for basic monitoring: 
const inboxState = await client.preferences.inboxState();
const address = inboxState.identifiers[0].identifier;
const inboxId = client.inboxId;
const installationId = client.installationId;
const conversations = await client.conversations.list();

console.log(`
✓ XMTP Client:
• InboxId: ${inboxId}
• Address: ${address}
• Conversations: ${conversations.length}
• Installations: ${inboxState.installations.length}
• InstallationId: ${installationId}
• Network: ${process.env.XMTP_ENV}`);

* console.log(\`Agent started. Address: ${xmtp.address}\`)  
* console.log(\`Environment: ${process.env.XMTP\_ENV}\`)  
* console.log(\`Listening for messages...\`)

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Content types

Base App supports various XMTP content types for rich messaging capabilities. This document outlines all supported content types, including custom types for Quick Actions and Intent. XMTP uses content types to define the structure and meaning of message types. We’ll outline the standard and custom XMTP content types you can utilize in your agent.

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XMTP Content Types

Text Messages
  • Content Type: xmtp.org/text:1.0
  • Purpose: Basic text messaging
  • Usage: Default for plain text
Attachments
  • Content Type: xmtp.org/attachment:1.0
  • Purpose: File attachments (inline)
  • Usage: Send files directly in messages
Remote Static Attachments
  • Content Type: xmtp.org/remoteStaticAttachment:1.0
  • Purpose: Remote file attachments via URLs
  • Usage: Reduce message size
Reactions
  • Content Type: xmtp.org/reaction:1.0
  • Purpose: Emoji reactions
  • Usage: React to messages with emojis
  • Note: Does not trigger read receipts
Replies
  • Content Type: xmtp.org/reply:1.0
  • Purpose: Threaded conversations
  • Usage: Reply to specific messages
Group Management
  • Content Types:
    • xmtp.org/group_membership_change:1.0
    • xmtp.org/group_updated:1.0
  • Purpose: Membership & group metadata updates
  • Usage: Automatic system messages
Read Receipts
  • Content Type: xmtp.org/readReceipt:1.0
  • Purpose: Read confirmations
  • Usage: Sent automatically
Transactions (Wallet Send Calls)
  • Content Type: xmtp.org/walletSendCalls:1.0
  • Purpose: Request wallet actions from users
Transaction Receipts
  • Content Type: xmtp.org/transactionReference:1.0
  • Purpose: Share blockchain transaction info

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Base App Content Types

There are content types developed by the Base App team for agents in Base App. Other XMTP clients may not support these content types. Quick Actions (coinbase.com/actions:1.0) Purpose: Present interactive buttons in a message Structure: 
type ActionsContent = {
  id: string;
  description: string;
  actions: Action[];
  expiresAt?: string;
};

type Action = {
  id: string;
  label: string;
  imageUrl?: string;
  style?: 'primary' | 'secondary' | 'danger';
  expiresAt?: string;
};
Validation Rules:
  • id, description are required
  • actions must be 1–10 items with unique IDs
  • Style must be one of: primary, secondary, danger
Fallback: 
[Description]

[1] [Action Label 1]
[2] [Action Label 2]
...
Reply with the number to select
Example: Payment Options 
{
  id: 'payment_alice_123',
  description: 'Choose amount to send to Alice',
  actions: [
    { id: 'send_10', label: 'Send $10', style: 'primary' },
    { id: 'send_20', label: 'Send $20', style: 'primary' },
    { id: 'custom_amount', label: 'Custom Amount', style: 'secondary' },
  ],
  expiresAt: '2024-12-31T23:59:59Z'
}
Manifest Embed Example

Example of Quick Actions message

Intent (coinbase.com/intent:1.0) Purpose: User expresses choice from Quick Actions Structure: 
type IntentContent = {
  id: string;
  actionId: string;
  metadata?: Record<string, string | number | boolean | null>;
};
Validation Rules:
  • id, actionId required
  • Must match corresponding Actions
  • metadata is optional, <10KB
Fallback: 
User selected action: [actionId]
Example: Intent Message 
{
  id: 'payment_alice_123',
  actionId: 'send_10',
  metadata: {
    timestamp: Date.now(),
    actionLabel: 'Send $10'
  }
}
Analytics dashboard with charts

Example of Intent Message

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Custom Transaction Trays

If you would like to display agent information such as favicon and branded title, utilize the metadata property of wallet send calls data.

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Example: Display agent information

// example of wallet send calls data shape{
  version: "1.0",
  from: request.from as `0x${string}`,
  chainId: this.networkConfig.chainId,
  calls: [
	{
	  ...
  metadata: {
    description: "Transfer token",
    ...other fields,
    hostname: "tba.chat",
    faviconUrl: "https://tba.chat/favicon",
    title: "Your favorite Agent"
  }	
 	}
  ]  
}
Transaction tray

transaction tray

You can send “GM” to tbachat.base.eth to get more details about message content types we support and get the firsthand experience on by interacting with our agent Our agent repo is found here

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Best practices

  1. Always validate content structures
  2. Provide fallbacks for unsupported clients
  3. Test across client versions
  4. Limit message and metadata size
  5. Follow XIP-67
  6. Your agent should respond to both direct messages and group chat messages (if applicable).
  7. For direct messages, it should automatically respond.
  8. We recommend reacting to messages with an emoji (like 👀or ⌛) to indicate the message was received, while the response is processing.
  9. For group chat messages, agents should only respond if they are mentioned with the “@” symbol and the agent’s name. (example “@bankr”), OR if the user replies directly to a message from the agent (using the reply content type).
For group chat messages, agents should only respond if they are mentioned with the ”@” symbol and the agent’s name. (example “@bankr”), OR if the user replies directly to a message from the agent (using the reply content type). Fill out the form here to submit your agent for review. Note, agents often go through multiple rounds of feedback before they are ready to be featured. Once approved, your agent will be featured in Base App. You will hear back from us within 5 business days. Need help or have feature requests? Visit https://community.xmtp.org/