# How to integrate Zerobounce MCP with Mastra AI

```json
{
  "title": "How to integrate Zerobounce MCP with Mastra AI",
  "toolkit": "Zerobounce",
  "toolkit_slug": "zerobounce",
  "framework": "Mastra AI",
  "framework_slug": "mastra-ai",
  "url": "https://composio.dev/toolkits/zerobounce/framework/mastra-ai",
  "markdown_url": "https://composio.dev/toolkits/zerobounce/framework/mastra-ai.md",
  "updated_at": "2026-05-06T08:34:42.363Z"
}
```

## Introduction

This guide walks you through connecting Zerobounce to Mastra AI using the Composio tool router. By the end, you'll have a working Zerobounce agent that can validate a list of 100 new signups, score this email for lead quality, check deliverability of mark@gmail.com through natural language commands.
This guide will help you understand how to give your Mastra AI agent real control over a Zerobounce account through Composio's Zerobounce MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.

## Also integrate Zerobounce with

- [OpenAI Agents SDK](https://composio.dev/toolkits/zerobounce/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/zerobounce/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/zerobounce/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/zerobounce/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/zerobounce/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/zerobounce/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/zerobounce/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/zerobounce/framework/cli)
- [Google ADK](https://composio.dev/toolkits/zerobounce/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/zerobounce/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/zerobounce/framework/ai-sdk)
- [LlamaIndex](https://composio.dev/toolkits/zerobounce/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/zerobounce/framework/crew-ai)

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

The Zerobounce MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Zerobounce account. It provides structured and secure access to your email validation and deliverability tools, so your agent can perform actions like validating emails, scoring leads, managing bulk jobs, and analyzing engagement—all automatically.
- Real-time email validation: Instantly check if email addresses are valid, risky, or undeliverable before sending campaigns or updating your lists.
- Bulk validation and processing: Upload files and process hundreds of emails or domains at once, with tools for tracking job status and retrieving results.
- AI-powered lead scoring: Score individual email addresses using Zerobounce AI to assess lead quality and prioritize outreach.
- Domain and pattern analysis: Identify common email address formats for any domain or run bulk domain searches to optimize your contact strategies.
- Allowlist and blocklist management: Easily update your allow and block lists to fine-tune which addresses pass or fail validation, keeping your lists clean and secure.

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `ZEROBOUNCE_ACTIVITY_DATA` | Get Activity Data | Tool to get activity data (opens, clicks, etc.) for a given email. use after confirming the email address to gauge engagement recency. |
| `ZEROBOUNCE_AI_SCORING_SINGLE` | AI Scoring Single Email | Tool to score a single email address using zerobounce ai. use when you need real-time email lead quality feedback before outreach. example prompt: "score the email mark@gmail.com." |
| `ZEROBOUNCE_ALLOW_BLOCK_LIST` | Allow or Block List | Tool to manage allowlist and blocklist for email validation. use when you need to programmatically add or modify custom filters before validating emails. |
| `ZEROBOUNCE_BATCH_VALIDATE_EMAILS` | Batch Validate Emails | Tool to validate a batch of email addresses in real time. use when you need to validate up to 200 emails at once with optional activity data. |
| `ZEROBOUNCE_DELETE_FILE` | Delete file | Tool to delete a file that was submitted for bulk validation. use when file status is 'complete'. |
| `ZEROBOUNCE_DOMAIN_SEARCH_FILE_STATUS` | Domain Search File Status | Tool to get the processing status of a file submitted for bulk domain search. use after submitting the file to poll status. |
| `ZEROBOUNCE_DOMAIN_SEARCH_GET_FILE` | Domain Search Get File | Tool to download the results file for a completed bulk domain search job. use when you have the file id and the job is complete. |
| `ZEROBOUNCE_DOMAIN_SEARCH_SEND_FILE` | Domain Search Send File | Tool to upload a file for bulk domain search. use when you have many domains in a csv/txt and need to lookup their details in bulk. |
| `ZEROBOUNCE_DOMAIN_SEARCH_SINGLE` | Domain Search Single | Tool to identify common email address formats for a given domain. use when you need to guess email patterns for a company based on its domain. |
| `ZEROBOUNCE_EMAIL_FINDER_DELETE_FILE` | Delete Email Finder File | Tool to delete a file that was submitted for bulk email finding. use when the file processing status is 'complete' and you need to remove it. |
| `ZEROBOUNCE_EMAIL_FINDER_FILE_STATUS` | Email Finder File Status | Tool to get the processing status of a file submitted for bulk email finding. use when you need to poll the progress of a bulk email-finder file upload. |
| `ZEROBOUNCE_EMAIL_FINDER_SEND_FILE` | Email Finder Send File | Tool to upload a file for bulk email finding. use when you have lists of names and domains to find emails in bulk via csv/txt upload. |
| `ZEROBOUNCE_EMAIL_FINDER_SINGLE` | Email Finder Single | Tool to find an email address for a given person and domain. use when you need to locate a professional email from a person's name and company domain. use after confirming domain or company info. |
| `ZEROBOUNCE_GET_API_USAGE` | Get API Usage | Tool to retrieve api usage statistics for a given period. use when you need usage metrics between two dates. |
| `ZEROBOUNCE_GET_CREDIT_BALANCE` | Get Credit Balance | Tool to retrieve your current zerobounce email validation credit balance. use when you need to monitor remaining credits to avoid service interruptions. |
| `ZEROBOUNCE_LIST_EVALUATOR` | List Evaluator | Tool to evaluate the quality of an email list. use when you have a list of emails and need a quick health check before full validation. |
| `ZEROBOUNCE_SEND_FILE` | Send File | Tool to upload a file for bulk email validation. use when you need to validate large lists of emails via csv or txt file. |
| `ZEROBOUNCE_VALIDATE_EMAIL` | Validate Email | Tool to validate a single email address in real time. use when you need to confirm deliverability and domain details before sending emails. |

## Supported Triggers

None listed.

## Creating MCP Server - Stand-alone vs Composio SDK

The Zerobounce MCP server is an implementation of the Model Context Protocol that connects your AI agent to Zerobounce. It provides structured and secure access so your agent can perform Zerobounce operations on your behalf through a secure, permission-based interface.
With Composio's managed implementation, you don't have to create your own developer app. For production, if you're building an end product, we recommend using your own credentials. The managed server helps you prototype fast and go from 0-1 faster.

## Step-by-step Guide

### 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

### 1. Getting API Keys for OpenAI and Composio

OpenAI API Key
- Go to the [OpenAI dashboard](https://platform.openai.com/settings/organization/api-keys) 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](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs).
- Go to Settings and copy your API key.
- This key lets your Mastra agent talk to Composio and reach Zerobounce through MCP.

### 2. Install dependencies

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

### 3. Set up environment variables

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
```bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here
```

### 4. Import libraries and validate environment

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
```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,
});
```

### 5. Create a Tool Router session for Zerobounce

What's happening:
- create spins up a short-lived MCP HTTP endpoint for this user
- The toolkits array contains "zerobounce" for Zerobounce access
- session.mcp.url is the MCP URL that Mastra's MCPClient will connect to
```typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["zerobounce"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Zerobounce MCP URL:", composioMCPUrl);
```

### 6. Configure Mastra MCP client and fetch tools

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 Zerobounce toolkit
```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);
```

### 7. Create the Mastra agent

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

### 8. Set up interactive chat interface

What's happening:
- messages keeps the full conversation history in Mastra's expected format
- agent.generate runs the agent with conversation history and Zerobounce 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
```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: {
        zerobounce: 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);
});
```

## Complete Code

```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: ["zerobounce"],
  });

  const composioMCPUrl = session.mcp.url;

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

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "zerobounce-mastra-agent",
    instructions: "You are an AI agent with Zerobounce 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: { zerobounce: 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 Zerobounce 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

## How to build Zerobounce MCP Agent with another framework

- [OpenAI Agents SDK](https://composio.dev/toolkits/zerobounce/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/zerobounce/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/zerobounce/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/zerobounce/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/zerobounce/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/zerobounce/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/zerobounce/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/zerobounce/framework/cli)
- [Google ADK](https://composio.dev/toolkits/zerobounce/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/zerobounce/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/zerobounce/framework/ai-sdk)
- [LlamaIndex](https://composio.dev/toolkits/zerobounce/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/zerobounce/framework/crew-ai)

## Related Toolkits

- [Reddit](https://composio.dev/toolkits/reddit) - Reddit is a social news platform with thriving user-driven communities (subreddits). It's the go-to place for discussion, content sharing, and viral marketing.
- [Facebook](https://composio.dev/toolkits/facebook) - Facebook is a social media and advertising platform for businesses and creators. It helps you connect, share, and manage content across your public Facebook Pages.
- [Linkedin](https://composio.dev/toolkits/linkedin) - LinkedIn is a professional networking platform for connecting, sharing content, and engaging with business opportunities. It's the go-to place for building your professional brand and unlocking new career connections.
- [Active campaign](https://composio.dev/toolkits/active_campaign) - ActiveCampaign is a marketing automation and CRM platform for managing email campaigns, sales pipelines, and customer segmentation. It helps businesses engage customers and drive growth through smart automation and targeted outreach.
- [ActiveTrail](https://composio.dev/toolkits/active_trail) - ActiveTrail is a user-friendly email marketing and automation platform. It helps you reach subscribers and automate campaigns with ease.
- [Ahrefs](https://composio.dev/toolkits/ahrefs) - Ahrefs is an SEO and marketing platform for site audits, keyword research, and competitor insights. It helps you improve search rankings and drive organic traffic.
- [Amcards](https://composio.dev/toolkits/amcards) - AMCards lets you create and mail personalized greeting cards online. Build stronger customer relationships with easy, automated card campaigns.
- [Beamer](https://composio.dev/toolkits/beamer) - Beamer is a news and changelog platform for in-app announcements and feature updates. It helps companies boost user engagement by sharing news where users are most active.
- [Benchmark email](https://composio.dev/toolkits/benchmark_email) - Benchmark Email is a platform for creating, sending, and tracking email campaigns. It's built to help you engage audiences and analyze results—all in one place.
- [Bigmailer](https://composio.dev/toolkits/bigmailer) - BigMailer is an email marketing platform for managing multiple brands with white-labeling and automation. It helps teams streamline campaigns and simplify integration with Amazon SES.
- [Brandfetch](https://composio.dev/toolkits/brandfetch) - Brandfetch is an API that delivers company logos, colors, and visual branding assets. It helps marketers and developers keep brand visuals consistent everywhere.
- [Brevo](https://composio.dev/toolkits/brevo) - Brevo is an all-in-one email and SMS marketing platform for transactional messaging, automation, and CRM. It helps businesses engage customers and streamline communications through powerful campaign tools.
- [Campayn](https://composio.dev/toolkits/campayn) - Campayn is an email marketing platform for creating, sending, and managing campaigns. It helps businesses engage contacts and grow audiences with easy-to-use tools.
- [Cardly](https://composio.dev/toolkits/cardly) - Cardly is a platform for creating and sending personalized direct mail to customers. It helps businesses break through the digital clutter by getting real engagement via physical mailboxes.
- [ClickSend](https://composio.dev/toolkits/clicksend) - ClickSend is a cloud-based SMS and email marketing platform for businesses. It streamlines communication by enabling quick message delivery and contact management.
- [Crustdata](https://composio.dev/toolkits/crustdata) - CrustData is an AI-powered data intelligence platform for real-time company and people data. It helps B2B sales teams, AI SDRs, and investors react to live business signals.
- [Curated](https://composio.dev/toolkits/curated) - Curated is a platform for collecting, curating, and publishing newsletters. It streamlines content aggregation and distribution for creators and teams.
- [Customerio](https://composio.dev/toolkits/customerio) - Customer.io is a customer engagement platform for targeted messaging across email, SMS, and push. Easily automate, segment, and track communications with your audience.
- [Cutt ly](https://composio.dev/toolkits/cutt_ly) - Cutt.ly is a URL shortening service for managing and analyzing links. Streamline your workflows with quick, trackable, and branded short URLs.
- [Demio](https://composio.dev/toolkits/demio) - Demio is webinar software built for marketers, offering both live and automated sessions with interactive features. It helps teams engage audiences and optimize lead generation through detailed analytics.

## Frequently Asked Questions

### What are the differences in Tool Router MCP and Zerobounce MCP?

With a standalone Zerobounce MCP server, the agents and LLMs can only access a fixed set of Zerobounce tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Zerobounce 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 Zerobounce tools.

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

Yes, absolutely. You can configure which Zerobounce 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 Zerobounce data and credentials are handled as safely as possible.

---
[See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)