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How to integrate Tomba MCP with Mastra AI

Connect Mastra AI to Tomba MCP. Find all leads from example.com domain, check if this email is disposable, and more using natural language, with authentication handled for you.

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Tomba is an Email Finder for B2B sales and email marketing. Find and verify professional emails to boost your outreach results.

25 Tools

Introduction

This guide walks you through connecting Tomba to Mastra AI using the Composio tool router. By the end, you'll have a working Tomba agent that can find professional emails, verify email addresses, enrich people and companies, search domain contacts, and manage lead lists through natural language commands.

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

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

Also integrate Tomba with

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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 Tomba tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Tomba 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 Tomba 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 Tomba MCP server, and what's possible with it?

The Tomba MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Tomba account. It provides structured and secure access to your B2B email finding, lead management, and account configuration tools, so your agent can perform actions like discovering leads, managing lists, validating domains, and monitoring account usage on your behalf.

  • Lead discovery and enrichment: Ask your agent to list available lead attributes or add new leads directly into your Tomba account for streamlined outreach.
  • Lead list management: Effortlessly retrieve, update, or delete lead lists, helping you stay organized and keep your data current.
  • Domain validation and status checks: Have your agent check if a domain is webmail or disposable to ensure better deliverability and lead quality.
  • API key and account management: Direct your agent to list, create, or revoke API keys, and review usage statistics to keep your Tomba integration secure and efficient.
  • Usage monitoring and reporting: Let your agent fetch up-to-date API usage statistics, keeping you informed about your plan limits and consumption.

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

Step by step09 STEPS
1

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
2

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 Tomba through MCP.
3

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
4

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
5

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
6

Create a Tool Router session for Tomba

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

  const composioMCPUrl = session.mcp.url;
  console.log("Tomba MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "tomba" for Tomba access
  • session.mcp.url is the MCP URL that Mastra's MCPClient will connect to
7

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 Tomba toolkit
8

Create the Mastra agent

typescript
const agent = new Agent({
    name: "tomba-mastra-agent",
    instructions: "You are an AI agent with Tomba 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
9

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: {
        tomba: 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 Tomba 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 Tomba 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: ["tomba"],
  });

  const composioMCPUrl = session.mcp.url;

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

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "tomba-mastra-agent",
    instructions: "You are an AI agent with Tomba 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: { tomba: 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 Tomba 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
TOOLS

Supported Tools

Every Tomba action and event your agent gets out of the box.

List Lead Attributes

Retrieves all custom lead attributes defined in your Tomba account.

Domain Status

Tool to check if a domain is webmail or disposable.

Enrich Company

Enrich one company from its domain; this does not look up a specific person.

Enrich Person

Enrich one person from an email address; use the company or combined actions for company-only or one-call person-and-company data.

Enrich Person and Company

Enrich both a person and their company from one email in one request; use the focused actions when only one entity is needed.

Find Article Author

Find an article author's professional contact data from its URL.

Find Professional Email

Find a professional email from company and person identifiers, optionally requesting an associated mobile phone number on non-managed calls.

Find Email From LinkedIn

Find the most likely professional email from a LinkedIn profile URL, optionally requesting all associated emails and, on non-managed calls, mobile phone data.

Find Phone Numbers

Find phone numbers by providing at least one of email, domain, or LinkedIn URL.

Get Domain Email Count

Return contact counts and department breakdown for a domain.

Get Domain Email Formats

Return detected email patterns for a domain.

Get Email Sources

Return public web sources where an email address was found.

Get Employee Locations

Return employee counts by country for a domain.

Delete API Key by ID

Tool to delete an API key by its numeric ID.

List API Keys

Tool to list all API keys.

Create Lead

Create a new lead in Tomba's lead database.

List Leads

Tool to list all leads.

Delete Leads List by ID

Tool to delete a leads list by ID.

List Lead Lists

List your Tomba lead lists, with optional page and page-size controls.

Update Leads List

Tool to update a leads list's name by ID.

Search Domain Contacts

Search a domain or company for professional contacts, with optional mobile phone enrichment on non-managed calls.

Get Usage Statistics

Tool to get API usage statistics.

Validate Phone Number

Validate and format a phone number.

Verify Email

Verify email deliverability and mailbox signals, optionally requesting an associated mobile phone number on non-managed calls.

Verify Emails

Verify up to 1000 emails by managing Tomba's asynchronous bulk job synchronously, with per-email charges and account-plan rate limits.

FRAMEWORKS

How to build Tomba MCP Agent with another framework

Claude Code logo

Claude Code

Use Tomba MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Tomba MCP with Claude Cowork

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Tomba MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Tomba MCP with Claude Agent SDK

Codex logo

Codex

Use Tomba MCP with Codex

OpenClaw logo

OpenClaw

Use Tomba MCP with OpenClaw

Hermes logo

Hermes

Use Tomba MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Tomba MCP with Atomic Agent

Google ADK logo

Google ADK

Use Tomba MCP with Google ADK

LangChain logo

LangChain

Use Tomba MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Tomba MCP with Vercel AI SDK

LlamaIndex logo

LlamaIndex

Use Tomba MCP with LlamaIndex

CrewAI logo

CrewAI

Use Tomba MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Tomba MCP with Pydantic AI

AutoGen logo

AutoGen

Use Tomba MCP with AutoGen

FAQ

Frequently asked questions

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

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 Tomba tools.

Yes, absolutely. You can configure which Tomba 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.

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 Tomba data and credentials are handled as safely as possible.

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