# How to integrate Mailersend MCP with Google ADK

```json
{
  "title": "How to integrate Mailersend MCP with Google ADK",
  "toolkit": "Mailersend",
  "toolkit_slug": "mailersend",
  "framework": "Google ADK",
  "framework_slug": "google-adk",
  "url": "https://composio.dev/toolkits/mailersend/framework/google-adk",
  "markdown_url": "https://composio.dev/toolkits/mailersend/framework/google-adk.md",
  "updated_at": "2026-05-12T10:18:19.514Z"
}
```

## Introduction

This guide walks you through connecting Mailersend to Google ADK using the Composio tool router. By the end, you'll have a working Mailersend agent that can add a new sending domain for your app, list all smtp users for our domain, check current api quota usage through natural language commands.
This guide will help you understand how to give your Google ADK agent real control over a Mailersend account through Composio's Mailersend MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.

## Also integrate Mailersend with

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

## TL;DR

Here's what you'll learn:
- Get a Mailersend account set up and connected to Composio
- Install the Google ADK and Composio packages
- Create a Composio Tool Router session for Mailersend
- Build an agent that connects to Mailersend through MCP
- Interact with Mailersend using natural language

## What is Google ADK?

Google ADK (Agents Development Kit) is Google's framework for building AI agents powered by Gemini models. It provides tools for creating agents that can use external services through the Model Context Protocol.
Key features include:
- Gemini Integration: Native support for Google's Gemini models
- MCP Toolset: Built-in support for Model Context Protocol tools
- Streamable HTTP: Connect to external services through streamable HTTP
- CLI and Web UI: Run agents via command line or web interface

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

The Mailersend MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mailersend account. It provides structured and secure access to your transactional email infrastructure, so your agent can perform actions like sending emails, managing domains, configuring webhooks, and monitoring API usage on your behalf.
- Seamless domain management: Register new sending domains, verify their status, and retrieve detailed configuration information to ensure reliable email delivery.
- Automated email and SMTP user setup: Quickly create SMTP users and API tokens as needed for secure and scalable application integration.
- Webhook configuration and event tracking: Set up and delete webhooks to monitor real-time email events such as sent, delivered, or opened messages, enabling proactive workflows and notifications.
- Recipient and quota insights: List recipients for specific domains and monitor your API usage to stay within account limits and optimize deliverability.
- Centralized resource discovery: Retrieve general API resources and overview endpoints to streamline Mailersend integration and administration directly from your agent.

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `MAILERSEND_CREATE_DOMAIN` | Create Sending Domain | Tool to add a new sending domain to MailerSend. Use when you need to register and configure a domain before sending emails. |
| `MAILERSEND_CREATE_SMTP_USER` | Create SMTP User | Tool to create a new SMTP user. Use after domain setup to obtain SMTP credentials. |
| `MAILERSEND_CREATE_TOKEN` | Create API Token | Creates a new API token with specified scopes (permissions) for a domain. The token allows programmatic access to MailerSend API endpoints based on granted scopes. WARNING: The token value is only displayed once upon creation and cannot be retrieved later. |
| `MAILERSEND_CREATE_WEBHOOK` | Create Webhook | Tool to create a new webhook for a MailerSend domain. Use after you have a domain ID and need to receive event notifications like sent, delivered, opened, etc. |
| `MAILERSEND_DELETE_WEBHOOK` | Delete Webhook | Tool to delete an existing webhook. Use when the webhook is no longer needed. Returns empty response on successful deletion (HTTP 204). |
| `MAILERSEND_GET_API_QUOTA` | Get API Quota | Tool to retrieve current API usage quota. Use when monitoring API rate limits to avoid exceeding allowed calls. |
| `MAILERSEND_GET_DOMAIN` | Get Domain | Tool to retrieve detailed information about a specific sending domain in MailerSend. Returns domain verification status (DKIM, SPF, MX, tracking), settings (click/open tracking, paused status), and metadata (creation/update timestamps). Use this when you need to check if a domain is properly verified and configured for sending emails, or to review domain-specific tracking settings. Note: For detailed DNS record values, use the Get Domain DNS Records action. |
| `MAILERSEND_GET_DOMAIN_RECIPIENTS` | List Domain Recipients | Tool to list recipients for a domain. Use after obtaining the domain ID to view recipients with optional pagination. |
| `MAILERSEND_GET_DOMAINS` | Get sending domains | Retrieve a paginated list of all sending domains configured in your MailerSend account. Use this to: - View all domains available for sending emails - Check domain verification and DNS status - Filter by verification status to find verified or unverified domains - Review domain settings like tracking and sending preferences Returns domain details including verification status, DNS configuration, and tracking settings. |
| `MAILERSEND_GET_GENERAL_RESOURCES` | Get general API resources | Tool to retrieve general API resources and information. Use when you need an overview of all MailerSend endpoints before constructing specific calls. |
| `MAILERSEND_GET_IDENTITIES` | List Sender Identities | Retrieves a paginated list of sender identities configured in your MailerSend account. Sender identities are the email addresses or domains authorized to send emails through MailerSend. Each identity includes verification status, reply-to configuration, domain association, and optional personal notes. Use this tool to discover available sender identities before sending emails or to verify which identities are ready for use. Returns: Paginated list of identity objects with metadata including verification status, domain details, and navigation links for pagination. |
| `MAILERSEND_GET_MESSAGES` | Get sent messages | Tool to retrieve a paginated list of sent messages. Use after sending emails to view message logs. |
| `MAILERSEND_GET_RECIPIENTS` | Get email recipients | Tool to retrieve a list of email recipients. Use when you need to list and filter recipients by list ID or search term. |
| `MAILERSEND_GET_SMS_ACTIVITY` | Get SMS Activity | Tool to retrieve SMS activity logs. Use when you need to fetch delivery status and logs of sent SMS messages. |
| `MAILERSEND_GET_SMS_INBOUNDS` | Get SMS Inbounds | Retrieve inbound SMS route configurations. Inbound routes define rules for forwarding incoming SMS messages to webhook URLs based on message content filters. Use this action when you need to: - List all configured SMS inbound routes - Filter routes by SMS number or enabled status - Review webhook forwarding configurations and filter rules |
| `MAILERSEND_GET_SMS_MESSAGES` | List SMS Messages | Retrieves a paginated list of SMS messages sent through the MailerSend API. Returns message details including sender, recipients, content, status, and timestamps. Use this to review sent SMS messages and track their delivery status. Note: For detailed activity tracking with filters (date ranges, status, phone numbers), use the SMS Activity endpoint instead. |
| `MAILERSEND_GET_SMS_NUMBERS` | Get SMS Numbers | Tool to retrieve a paginated list of SMS phone numbers. Use after purchasing numbers to fetch available SMS numbers. |
| `MAILERSEND_GET_SMS_RECIPIENTS` | Get SMS recipients | Tool to retrieve a list of SMS recipients. Use when you need to list and paginate SMS recipients, optionally filtering by SMS number ID and/or recipient status. |
| `MAILERSEND_GET_SMTP_USERS` | Get SMTP users | Tool to retrieve a list of SMTP users. Use when you need to list and paginate SMTP users. |
| `MAILERSEND_GET_TEMPLATES` | Get email templates | Retrieves a paginated list of email templates from your MailerSend account. Use this tool when you need to: - List all available email templates - Filter templates by domain ID - Browse templates with pagination - Check template details like name, type, and creation date Returns template metadata including IDs, names, types, and timestamps. For full template content, use a separate get single template endpoint. |
| `MAILERSEND_GET_TOKENS` | Get API Tokens | Retrieves a paginated list of API tokens associated with your MailerSend account. Returns token details including ID, name, status, creation date, and assigned scopes/permissions. Requires 'tokens_full' scope. |
| `MAILERSEND_GET_USERS` | Get users | Tool to retrieve a list of users associated with your account. Use after authenticating with a valid API token. |
| `MAILERSEND_GET_WEBHOOKS` | List webhooks | Tool to retrieve a list of webhooks. Use when you need to list and paginate all configured webhooks, optionally filtering by domain. |

## Supported Triggers

None listed.

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

The Mailersend MCP server is an implementation of the Model Context Protocol that connects your AI agent to Mailersend. It provides structured and secure access so your agent can perform Mailersend 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:
- A Google API key for Gemini models
- A Composio account and API key
- Python 3.9 or later installed
- Basic familiarity with Python

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

Google API Key
- Go to [Google AI Studio](https://aistudio.google.com/app/apikey) and create an API key.
- Copy the key and keep it safe. You will put this in GOOGLE_API_KEY.
Composio API Key and User ID
- Log in to the [Composio dashboard](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs).
- Go to Settings → API Keys and copy your Composio API key. Use this for COMPOSIO_API_KEY.
- Decide on a stable user identifier to scope sessions, often your email or a user ID. Use this for COMPOSIO_USER_ID.

### 2. Install dependencies

Inside your virtual environment, install the required packages.
What's happening:
- google-adk is Google's Agents Development Kit
- composio connects your agent to Mailersend via MCP
- python-dotenv loads environment variables
```bash
pip install google-adk composio python-dotenv
```

### 3. Set up ADK project

Set up a new Google ADK project.
What's happening:
- This creates an agent folder with a root agent file and .env file
```bash
adk create my_agent
```

### 4. Set environment variables

Save all your credentials in the .env file.
What's happening:
- GOOGLE_API_KEY authenticates with Google's Gemini models
- COMPOSIO_API_KEY authenticates with Composio
- COMPOSIO_USER_ID identifies the user for session management
```bash
GOOGLE_API_KEY=your-google-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id-or-email
```

### 5. Import modules and validate environment

What's happening:
- os reads environment variables
- Composio is the main Composio SDK client
- GoogleProvider declares that you are using Google ADK as the agent runtime
- Agent is the Google ADK LLM agent class
- McpToolset lets the ADK agent call MCP tools over HTTP
```python
import os
import warnings

from composio import Composio
from dotenv import load_dotenv
from google.adk.agents.llm_agent import Agent
from google.adk.tools.mcp_tool.mcp_session_manager import StreamableHTTPConnectionParams
from google.adk.tools.mcp_tool.mcp_toolset import McpToolset

load_dotenv()

warnings.filterwarnings("ignore", message=".*BaseAuthenticatedTool.*")

GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not GOOGLE_API_KEY:
    raise ValueError("GOOGLE_API_KEY is not set in the environment.")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment.")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment.")
```

### 6. Create Composio client and Tool Router session

What's happening:
- Authenticates to Composio with your API key
- Declares Google ADK as the provider
- Spins up a short-lived MCP endpoint for your user and selected toolkit
- Stores the MCP HTTP URL for the ADK MCP integration
```python
composio_client = Composio(api_key=COMPOSIO_API_KEY)

composio_session = composio_client.create(
    user_id=COMPOSIO_USER_ID,
    toolkits=["mailersend"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url,
print(f"Composio MCP URL: {COMPOSIO_MCP_URL}")
```

### 7. Set up the McpToolset and create the Agent

What's happening:
- Connects the ADK agent to the Composio MCP endpoint through McpToolset
- Uses Gemini as the model powering the agent
- Lists exact tool names in instruction to reduce misnamed tool calls
```python
composio_toolset = McpToolset(
    connection_params=StreamableHTTPConnectionParams(
        url=COMPOSIO_MCP_URL,
        headers={"x-api-key": COMPOSIO_API_KEY}
    )
)

root_agent = Agent(
    model="gemini-2.5-flash",
    name="composio_agent",
    description="An agent that uses Composio tools to perform actions.",
    instruction=(
        "You are a helpful assistant connected to Composio. "
        "You have the following tools available: "
        "COMPOSIO_SEARCH_TOOLS, COMPOSIO_MULTI_EXECUTE_TOOL, "
        "COMPOSIO_MANAGE_CONNECTIONS, COMPOSIO_REMOTE_BASH_TOOL, COMPOSIO_REMOTE_WORKBENCH. "
        "Use these tools to help users with Mailersend operations."
    ),
    tools=[composio_toolset],
)

print("\nAgent setup complete. You can now run this agent directly ;)")
```

### 8. Run the agent

Execute the agent from the project root. The web command opens a web portal where you can chat with the agent.
What's happening:
- adk run runs the agent in CLI mode
- adk web . opens a web UI for interactive testing
```bash
# Run in CLI mode
adk run my_agent

# Or run in web UI mode
adk web
```

## Complete Code

```python
import os
import warnings

from composio import Composio
from composio_google import GoogleProvider
from dotenv import load_dotenv
from google.adk.agents.llm_agent import Agent
from google.adk.tools.mcp_tool.mcp_session_manager import StreamableHTTPConnectionParams
from google.adk.tools.mcp_tool.mcp_toolset import McpToolset

load_dotenv()
warnings.filterwarnings("ignore", message=".*BaseAuthenticatedTool.*")

GOOGLE_API_KEY = os.getenv("GOOGLE_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not GOOGLE_API_KEY:
    raise ValueError("GOOGLE_API_KEY is not set in the environment.")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment.")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment.")

composio_client = Composio(api_key=COMPOSIO_API_KEY, provider=GoogleProvider())

composio_session = composio_client.create(
    user_id=COMPOSIO_USER_ID,
    toolkits=["mailersend"],
)

COMPOSIO_MCP_URL = composio_session.mcp.url


composio_toolset = McpToolset(
    connection_params=StreamableHTTPConnectionParams(
        url=COMPOSIO_MCP_URL,
        headers={"x-api-key": COMPOSIO_API_KEY}
    )
)

root_agent = Agent(
    model="gemini-2.5-flash",
    name="composio_agent",
    description="An agent that uses Composio tools to perform actions.",
    instruction=(
        "You are a helpful assistant connected to Composio. "
        "You have the following tools available: "
        "COMPOSIO_SEARCH_TOOLS, COMPOSIO_MULTI_EXECUTE_TOOL, "
        "COMPOSIO_MANAGE_CONNECTIONS, COMPOSIO_REMOTE_BASH_TOOL, COMPOSIO_REMOTE_WORKBENCH. "
        "Use these tools to help users with Mailersend operations."
    ),  
    tools=[composio_toolset],
)

print("\nAgent setup complete. You can now run this agent directly ;)")
```

## Conclusion

You've successfully integrated Mailersend with the Google ADK through Composio's MCP Tool Router. Your agent can now interact with Mailersend using natural language commands.
Key takeaways:
- The Tool Router approach dynamically routes requests to the appropriate Mailersend tools
- Environment variables keep your credentials secure and separate from code
- Clear agent instructions reduce tool calling errors
- The ADK web UI provides an interactive interface for testing and development
You can extend this setup by adding more toolkits to the toolkits array in your session configuration.

## How to build Mailersend MCP Agent with another framework

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

## Related Toolkits

- [Gmail](https://composio.dev/toolkits/gmail) - Gmail is Google's email service with powerful spam protection, search, and G Suite integration. It keeps your inbox organized and makes communication fast and reliable.
- [Outlook](https://composio.dev/toolkits/outlook) - Outlook is Microsoft's email and calendaring platform for unified communications and scheduling. It helps users stay organized with powerful email, contacts, and calendar management.
- [Slack](https://composio.dev/toolkits/slack) - Slack is a channel-based messaging platform for teams and organizations. It helps people collaborate in real time, share files, and connect all their tools in one place.
- [Gong](https://composio.dev/toolkits/gong) - Gong is a platform for video meetings, call recording, and team collaboration. It helps teams capture conversations, analyze calls, and turn insights into action.
- [Microsoft teams](https://composio.dev/toolkits/microsoft_teams) - Microsoft Teams is a collaboration platform that combines chat, meetings, and file sharing within Microsoft 365. It keeps distributed teams connected and productive through seamless virtual communication.
- [Slackbot](https://composio.dev/toolkits/slackbot) - Slackbot is a conversational automation tool for Slack that handles reminders, notifications, and automated responses. It boosts team productivity by streamlining onboarding, answering FAQs, and managing timely alerts—all right inside Slack.
- [2chat](https://composio.dev/toolkits/_2chat) - 2chat is an API platform for WhatsApp and multichannel text messaging. It streamlines chat automation, group management, and real-time messaging for developers.
- [Agent mail](https://composio.dev/toolkits/agent_mail) - Agent mail provides AI agents with dedicated email inboxes for sending, receiving, and managing emails. It empowers agents to communicate autonomously with people, services, and other agents—no human intervention needed.
- [Basecamp](https://composio.dev/toolkits/basecamp) - Basecamp is a project management and team collaboration tool by 37signals. It helps teams organize tasks, share files, and communicate efficiently in one place.
- [Chatwork](https://composio.dev/toolkits/chatwork) - Chatwork is a team communication platform with group chats, file sharing, and task management. It helps businesses boost collaboration and streamline productivity.
- [Clickmeeting](https://composio.dev/toolkits/clickmeeting) - ClickMeeting is a cloud-based platform for running online meetings and webinars. It helps businesses and individuals host, manage, and engage virtual audiences with ease.
- [Confluence](https://composio.dev/toolkits/confluence) - Confluence is Atlassian's team collaboration and knowledge management platform. It helps your team organize, share, and update documents and project content in one secure workspace.
- [Dailybot](https://composio.dev/toolkits/dailybot) - DailyBot streamlines team collaboration with chat-based standups, reminders, and polls. It keeps work flowing smoothly in your favorite messaging platforms.
- [Dialmycalls](https://composio.dev/toolkits/dialmycalls) - Dialmycalls is a mass notification service for sending voice and text messages to contacts. It helps teams and organizations quickly broadcast urgent alerts and updates.
- [Dialpad](https://composio.dev/toolkits/dialpad) - Dialpad is a cloud-based business phone and contact center system for teams. It unifies voice, video, messaging, and meetings across your devices.
- [Discord](https://composio.dev/toolkits/discord) - Discord is a real-time messaging and VoIP platform for communities and teams. It lets users chat, share media, and collaborate across public and private channels.
- [Discordbot](https://composio.dev/toolkits/discordbot) - Discordbot is an automation tool for Discord servers that handles moderation, messaging, and user engagement. It helps communities run smoothly by automating routine and complex tasks.
- [Echtpost](https://composio.dev/toolkits/echtpost) - Echtpost is a secure digital communication platform for encrypted document and message exchange. It ensures confidential data stays private and protected during transmission.
- [Egnyte](https://composio.dev/toolkits/egnyte) - Egnyte is a cloud-based platform for secure file sharing, storage, and governance. It helps teams collaborate efficiently while maintaining data compliance and security.
- [Google Meet](https://composio.dev/toolkits/googlemeet) - Google Meet is a secure video conferencing platform for virtual meetings, chat, and screen sharing. It helps teams connect, collaborate, and communicate seamlessly from anywhere.

## Frequently Asked Questions

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

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

### Can I use Tool Router MCP with Google ADK?

Yes, you can. Google ADK 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 Mailersend tools.

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

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

---
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