How to integrate Omnisend MCP with Mastra AI

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Introduction

This guide walks you through connecting Omnisend to Mastra AI using the Composio tool router. By the end, you'll have a working Omnisend agent that can add new subscribers from latest signups, update contact email preferences in bulk, list all products for upcoming campaign through natural language commands.

This guide will help you understand how to give your Mastra AI agent real control over a Omnisend account through Composio's Omnisend MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Omnisend with

TL;DR

Here's what you'll learn:
  • Set up your environment so Mastra, OpenAI, and Composio work together
  • Create a Tool Router session in Composio that exposes Omnisend tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Omnisend tool definitions and attach them as a toolset
  • Build a Mastra agent that can reason, call tools, and return structured results
  • Run an interactive CLI where you can chat with your Omnisend agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

  • MCP Client: Built-in support for Model Context Protocol servers
  • Toolsets: Organize tools into logical groups
  • Step Callbacks: Monitor and debug agent execution
  • OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

What is the Omnisend MCP server, and what's possible with it?

The Omnisend MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Omnisend account. It provides structured and secure access to your ecommerce marketing data, so your agent can manage contacts, automate batch operations, update products, and streamline campaign preparation for your store.

  • Bulk contact and product management: Effortlessly create or update large sets of contacts or products in one go, perfect for onboarding new subscribers or syncing your catalog.
  • Individual contact handling: Retrieve, update, or enrich detailed contact profiles, making it easy for your agent to personalize outreach or manage subscriptions.
  • Batch job automation and tracking: Initiate batch operations and monitor their progress, status, and results to ensure smooth processing of large datasets.
  • Product catalog maintenance: List, review, or delete products directly from your Omnisend account, keeping your store's offerings up to date for campaigns.
  • Contact segmentation and filtering: Fetch paginated and filtered contact lists, enabling targeted marketing actions and smarter audience management.

Supported Tools & Triggers

Tools
Add Cart ProductTool to add a product to a cart in Omnisend (v3 API).
Create BatchTool to create a new batch operation for multiple items.
Create CartTool to create a new shopping cart in Omnisend.
Create CategoryTool to create a new category in Omnisend.
Create OrderTool to create a new order in Omnisend v3 API.
Create or Update ContactTool to create or update a contact in Omnisend.
Create ProductTool to create a new product in the Omnisend product catalog.
Create Product CategoryTool to create a new product category in the Omnisend catalog.
Delete CartTool to delete a cart from Omnisend by its ID (v3 API).
Delete CategoryTool to remove a category from Omnisend by its ID.
Delete OrderTool to delete an order from Omnisend by its ID.
Delete ProductTool to remove a product from Omnisend by its ID.
Delete Product CategoryTool to remove a product category from Omnisend by its ID.
Get BatchesTool to retrieve a list of batch operations.
Get Batch InformationTool to retrieve information about a specific batch by ID.
Get Batch ItemTool to retrieve a specific item within a batch by batchID and itemID.
Get Batch ItemsTool to retrieve processed items of a specific batch by ID.
Get BrandTool to retrieve information about the current authenticated brand.
Get CartTool to retrieve a specific cart by ID from Omnisend v3 API.
Get CategoryTool to retrieve details of a specific category by ID.
Get ContactTool to retrieve details of a single contact by ID.
Get OrderTool to retrieve details of a specific order by ID.
Get ProductTool to retrieve details of a specific product by ID from Omnisend.
Get Product CategoryTool to retrieve a specific product category by ID.
List CampaignsTool to retrieve a paginated list of campaigns with optional filtering by status and type.
List CartsTool to retrieve a paginated list of carts with optional filtering.
List CategoriesTool to retrieve a paginated list of product categories.
List ContactsTool to retrieve a paginated list of contacts with optional filtering.
List EventsTool to retrieve all custom events created in Omnisend app.
List Product CategoriesTool to retrieve a paginated list of product categories from the Omnisend catalog.
List ProductsTool to retrieve a paginated list of products.
Remove Cart ProductTool to remove a product from a cart in Omnisend.
Replace CartTool to replace an existing cart in Omnisend using the v3 API.
Replace Cart ProductTool to replace a product in a cart using Omnisend v3 API.
Replace CategoryTool to replace a category's title by ID.
Replace OrderTool to completely replace an existing order in Omnisend.
Replace ProductTool to replace an existing product in the Omnisend catalog.
Send EventTool to send a customer event to Omnisend.
Update CartTool to partially update a cart in Omnisend (v3 API).
Update Cart ProductTool to update a product in a cart (v3 API).
Update ContactTool to update fields of an existing contact by ID.
Update Order StatusTool to partially update an order status in Omnisend (v3 API).
Update Product CategoryTool to update an existing product category title in Omnisend.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Prerequisites

Before starting, make sure you have:
  • Node.js 18 or higher
  • A Composio account with an active API key
  • An OpenAI API key
  • Basic familiarity with TypeScript

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key.
  • You need credits or a connected billing setup to use the models.
  • Store the key somewhere safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Go to Settings and copy your API key.
  • This key lets your Mastra agent talk to Composio and reach Omnisend through MCP.

Install dependencies

bash
npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenv

Install the required packages.

What's happening:

  • @composio/core is the Composio SDK for creating MCP sessions
  • @mastra/core provides the Agent class
  • @mastra/mcp is Mastra's MCP client
  • @ai-sdk/openai is the model wrapper for OpenAI
  • dotenv loads environment variables from .env

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your requests to Composio
  • COMPOSIO_USER_ID tells Composio which user this session belongs to
  • OPENAI_API_KEY lets the Mastra agent call OpenAI models

Import libraries and validate environment

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey as string,
});
What's happening:
  • dotenv/config auto loads your .env so process.env.* is available
  • openai gives you a Mastra compatible model wrapper
  • Agent is the Mastra agent that will call tools and produce answers
  • MCPClient connects Mastra to your Composio MCP server
  • Composio is used to create a Tool Router session

Create a Tool Router session for Omnisend

typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["omnisend"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Omnisend MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "omnisend" for Omnisend access
  • session.mcp.url is the MCP URL that Mastra's MCPClient will connect to

Configure Mastra MCP client and fetch tools

typescript
const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);
What's happening:
  • MCPClient takes an id for this client and a list of MCP servers
  • The headers property includes the x-api-key for authentication
  • getTools fetches the tool definitions exposed by the Omnisend toolkit

Create the Mastra agent

typescript
const agent = new Agent({
    name: "omnisend-mastra-agent",
    instructions: "You are an AI agent with Omnisend tools via Composio.",
    model: "openai/gpt-5",
  });
What's happening:
  • Agent is the core Mastra agent
  • name is just an identifier for logging and debugging
  • instructions guide the agent to use tools instead of only answering in natural language
  • model uses openai("gpt-5") to configure the underlying LLM

Set up interactive chat interface

typescript
let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\n");

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: "> ",
});

rl.prompt();

rl.on("line", async (userInput: string) => {
  const trimmedInput = userInput.trim();

  if (["exit", "quit", "bye"].includes(trimmedInput.toLowerCase())) {
    console.log("\nGoodbye!");
    rl.close();
    process.exit(0);
  }

  if (!trimmedInput) {
    rl.prompt();
    return;
  }

  messages.push({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        omnisend: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    console.log("\nSession ended.");
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});
What's happening:
  • messages keeps the full conversation history in Mastra's expected format
  • agent.generate runs the agent with conversation history and Omnisend toolsets
  • maxSteps limits how many tool calls the agent can take in a single run
  • onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

Here's the complete code to get you started with Omnisend and Mastra AI:

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({ apiKey: composioAPIKey as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["omnisend"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      omnisend: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "omnisend-mastra-agent",
    instructions: "You are an AI agent with Omnisend tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: "> ",
  });

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { omnisend: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Omnisend through Composio's Tool Router. You can extend this further by:
  • Adding other toolkits like Gmail, Slack, or GitHub
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows

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FAQ

What are the differences in Tool Router MCP and Omnisend MCP?

With a standalone Omnisend MCP server, the agents and LLMs can only access a fixed set of Omnisend tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Omnisend and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with Mastra AI?

Yes, you can. Mastra AI fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Omnisend tools.

Can I manage the permissions and scopes for Omnisend while using Tool Router?

Yes, absolutely. You can configure which Omnisend scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Omnisend data and credentials are handled as safely as possible.

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