building-agents

name	building-agents
description	Core XMTP Agent SDK setup and patterns. Use when creating new agents, handling messages, setting up middleware, or configuring environment variables. Triggers on agent setup, XMTP configuration, message handling, or middleware implementation.
license	MIT
metadata	{"author":"xmtp","version":"1.0.0"}

XMTP agent basics

Build event-driven, middleware-powered messaging agents on the XMTP network using the @xmtp/agent-sdk.

When to apply

Reference these guidelines when:

• Creating a new XMTP agent
• Setting up environment variables
• Handling text messages and events
• Implementing middleware
• Using filters and context helpers

Rule categories by priority

Priority	Category	Impact	Prefix
1	Setup	CRITICAL	setup-
2	Events	HIGH	events-
3	Middleware	MEDIUM	middleware-
4	Filters	MEDIUM	filters-

Quick reference

Setup (CRITICAL)

• setup-environment - Configure environment variables for agent
• setup-from-env - Create agent using Agent.createFromEnv()
• setup-manual - Manual agent creation with signer

Events (HIGH)

• events-text - Handle text messages
• events-lifecycle - Handle start/stop events
• events-conversation - Handle new DM and group conversations
• events-message-types - Handle different message types (reaction, reply, attachment)

Middleware (MEDIUM)

• middleware-basics - Create and register middleware
• middleware-error-handling - Handle errors in middleware chain
• middleware-command-router - Use CommandRouter for slash commands

Filters (MEDIUM)

• filters-message-types - Filter by message type
• filters-sender - Filter out self-messages

Installation

npm install @xmtp/agent-sdk
# or
yarn add @xmtp/agent-sdk

SDK 2.0+ uses unified exports: import everything from @xmtp/agent-sdk (no /debug, /middleware, /user, /util subpaths).

Quick start

import { Agent, getTestUrl } from "@xmtp/agent-sdk";

// Create agent using environment variables
const agent = await Agent.createFromEnv();

// Handle text messages
agent.on("text", async (ctx) => {
  await ctx.conversation.sendText("Hello from my XMTP Agent!");
});

// Log when ready
agent.on("start", () => {
  console.log(`Agent online: ${getTestUrl(agent.client)}`);
});

await agent.start();

Environment variables

Variable	Purpose	Example
XMTP_WALLET_KEY	Private key for wallet	0x1234...abcd
XMTP_DB_ENCRYPTION_KEY	Database encryption key	0xabcd...1234
XMTP_ENV	Network environment	dev or production
XMTP_DB_DIRECTORY	Database directory	./data

How to use

Read individual rule files for detailed explanations:

rules/setup-environment.md
rules/events-text.md
rules/middleware-basics.md