How to integrate Clearout MCP with Mastra AI

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Introduction

This guide walks you through connecting Clearout to Mastra AI using the Composio tool router. By the end, you'll have a working Clearout agent that can validate a list of emails for deliverability, check if this email is a business account, find the most likely domain for acme corp, download results from my last bulk email finder job through natural language commands.

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

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

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

The Clearout MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Clearout account. It provides structured and secure access to email validation, prospecting, and enrichment tools, so your agent can perform actions like verifying email addresses, finding business contacts, checking domain details, and bulk-processing lists on your behalf.

  • AI-powered email verification: Instantly validate single or bulk email addresses to ensure deliverability and reduce bounce rates.
  • Email prospecting and enrichment: Find emails for people or companies, complete missing contact data, and verify if accounts are business or personal.
  • Domain and company intelligence: Retrieve company domains from names, fetch MX records, or pull WHOIS information to understand your leads and their infrastructure.
  • Disposable and catch-all detection: Check if an email is temporary or if a domain accepts all mail, helping you maintain list quality and avoid spam traps.
  • Bulk job automation: Upload, process, monitor, cancel, and download results for large-scale email finding and verification tasks, all through your agent.

Supported Tools & Triggers

Tools
Autocomplete Company to DomainTool to autocomplete company names to probable domains with confidence scores.
Business Account VerifyTool to check if an email belongs to a business/work account.
Catch-All VerifyTool to check if an email domain is catch-all.
Verify Disposable EmailTool to check if an email is from a disposable provider.
Find Domain MX RecordsTool to retrieve MX records for a domain in priority order.
Fetch Domain WHOIS InformationTool to fetch WHOIS record for a domain.
Bulk Email FinderTool to upload a CSV or XLSX contacts file for bulk email finding.
Cancel Bulk Email Finder JobTool to cancel a running bulk email finder job.
Bulk Email Finder Result DownloadTool to generate a bulk email finder result download URL.
Bulk Email VerifyTool to upload a CSV or XLSX file for bulk email verification.
Cancel Bulk Email Verification JobTool to cancel a running bulk email verification job.
Bulk Email Verify Progress StatusTool to retrieve progress for a bulk email verification job.
Bulk Email Verify Result DownloadTool to obtain a temporary URL for bulk email verification results.
Email Verify Get CreditsTool to fetch available email verification credits.
Instant Email VerifierTool to instantly verify a single email address.
Verify Free Email AccountTool to detect if an email is from a free email service provider.
Verify Gibberish EmailTool to verify if an email address is gibberish.
Reverse Lookup Company by DomainTool to find company information by domain.
Reverse Lookup Person by EmailTool to retrieve a person’s profile from an email address.
Find Person via LinkedIn URLTool to discover person information via a LinkedIn profile URL.
Role Account VerifierTool to determine if an email is a role-based account.

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

What is Tool Router?

Composio's Tool Router 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 Tool Router

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

How the Tool Router works

The Tool Router 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 Clearout 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 Clearout

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

  const composioMCPUrl = session.mcp.url;
  console.log("Clearout MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "clearout" for Clearout 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 Clearout toolkit

Create the Mastra agent

typescript
const agent = new Agent({
    name: "clearout-mastra-agent",
    instructions: "You are an AI agent with Clearout 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: {
        clearout: 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 Clearout 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 Clearout 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: ["clearout"],
  });

  const composioMCPUrl = session.mcp.url;

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

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "clearout-mastra-agent",
    instructions: "You are an AI agent with Clearout 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: { clearout: 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 Clearout 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 Clearout MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Clearout MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Clearout MCP with Claude Agent SDK

Google ADK

Google ADK

Use Clearout MCP with Google ADK

LangChain

LangChain

Use Clearout MCP with LangChain

Vercel AI SDK

Vercel AI SDK

Use Clearout MCP with Vercel AI SDK

LlamaIndex

LlamaIndex

Use Clearout MCP with LlamaIndex

CrewAI

CrewAI

Use Clearout MCP with CrewAI

FAQ

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

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

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

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

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