How to integrate Handwrytten MCP with Google ADK

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Introduction

This guide walks you through connecting Handwrytten to Google ADK using the Composio tool router. By the end, you'll have a working Handwrytten agent that can send a thank you card to john doe, schedule a handwritten birthday note delivery, list all pending handwrytten orders through natural language commands.

This guide will help you understand how to give your Google ADK agent real control over a Handwrytten account through Composio's Handwrytten 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:
  • Get a Handwrytten account set up and connected to Composio
  • Install the Google ADK and Composio packages
  • Create a Composio Tool Router session for Handwrytten
  • Build an agent that connects to Handwrytten through MCP
  • Interact with Handwrytten 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 Handwrytten MCP server, and what's possible with it?

The Handwrytten MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Handwrytten account. It provides structured and secure access so your agent can perform Handwrytten operations on your behalf.

Supported Tools & Triggers

Tools
Add RecipientTool to add a recipient address to the user's addressbook in Handwrytten.
Calculate Order TaxesTool to calculate taxes for Handwrytten basket orders.
Check AuthenticationTool to verify API key authentication validity for Handwrytten.
Clear BasketTool to clear all items from the shopping basket.
Create TemplateTool to create a new template for the current user.
Create User AddressTool to create a new user address in Handwrytten.
Delete Custom ImageTool to delete a custom image/logo from Handwrytten.
Delete Recipient AddressTool to delete one or more recipient addresses from user's profile.
Delete TemplateTool to delete a user's template by its ID.
Get Basket (New Method)Tool to retrieve the user's basket using the new method.
Get Basket CountTool to retrieve the count of items currently in the basket.
Get Basket ItemTool to retrieve a basket item by its ID from Handwrytten.
Get Card DetailsTool to get detailed information about a specific card in the Handwrytten catalog.
Get List of AddressesTool to retrieve a list of all addresses associated with the user's account.
Get Random CardsTool to retrieve random cards from Handwrytten.
Get Template DetailsTool to get detailed information about a card text template in the Handwrytten catalog.
Get Current User InfoTool to retrieve information about the currently authenticated user.
Get User AddressTool to retrieve the authenticated user's address and billing information.
List Basket Orders GroupedTool to list all basket orders grouped by basket.
List Past BasketsTool to retrieve a list of user's past baskets.
List CardsTool to retrieve a list of available Handwrytten cards with optional filtering and pagination.
List CategoriesTool to retrieve the list of available card categories from Handwrytten.
List CountriesTool to retrieve the list of countries available in Handwrytten.
List Credit CardsTool to list all credit cards associated with the Handwrytten account.
List FontsTool to retrieve the list of available handwriting fonts.
List Fonts for CustomizerTool to list fonts available for use with the card customizer.
List Gift CardsTool to retrieve the list of available gift cards with their denominations and pricing.
List Custom User ImagesTool to retrieve a list of custom user images uploaded to Handwrytten.
List InsertsTool to retrieve a list of available inserts from Handwrytten.
List OrdersTool to retrieve a list of user's past orders from Handwrytten.
List Orders GroupedTool to retrieve the user's order history grouped by basket.
List Past OrdersTool to retrieve a list of user's past orders from Handwrytten API.
List RecipientsTool to retrieve a list of recipient addresses that the user has previously saved.
List SignaturesTool to retrieve the list of available signatures for use in card orders.
List StatesTool to retrieve the list of states/provinces available in Handwrytten.
List Template CategoriesTool to retrieve the list of available template categories from Handwrytten.
List TemplatesTool to retrieve a list of card text templates from Handwrytten.
Logout UserTool to logout user from Handwrytten application.
Place Order in BasketTool to add an order to the basket in Handwrytten.
Register UserTool to register a new Handwrytten user account.
Request Password ResetTool to request a password reset email for a Handwrytten account.
Set Default AddressTool to set a default return address for the user in Handwrytten.
Set Test ModeTool to set test mode for the current Handwrytten user.
Update Basket ItemTool to update an existing basket item in Handwrytten.
Update Billing InformationTool to update user billing information (country, zip, address) for tax calculations in Handwrytten.
Update RecipientTool to update a recipient address in the user's addressbook in Handwrytten.
Update TemplateTool to update an existing user template in Handwrytten.
Upload Custom LogoTool to upload a custom image (logo or cover) to Handwrytten for use with custom cards.

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:
  • A Google API key for Gemini models
  • A Composio account and API key
  • Python 3.9 or later installed
  • Basic familiarity with Python

Getting API Keys for Google and Composio

Google API Key
  • Go to Google AI Studio 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.
  • 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.

Install dependencies

bash
pip install google-adk composio python-dotenv

Inside your virtual environment, install the required packages.

What's happening:

  • google-adk is Google's Agents Development Kit
  • composio connects your agent to Handwrytten via MCP
  • python-dotenv loads environment variables

Set up ADK project

bash
adk create my_agent

Set up a new Google ADK project.

What's happening:

  • This creates an agent folder with a root agent file and .env file

Set environment variables

bash
GOOGLE_API_KEY=your-google-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id-or-email

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

Import modules and validate environment

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.")
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

Create Composio client and Tool Router session

python
composio_client = Composio(api_key=COMPOSIO_API_KEY)

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

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

Set up the McpToolset and create the Agent

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 Handwrytten operations."
    ),
    tools=[composio_toolset],
)

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

Run the agent

bash
# Run in CLI mode
adk run my_agent

# Or run in web UI mode
adk web

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

Complete Code

Here's the complete code to get you started with Handwrytten and Google ADK:

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=["handwrytten"],
)

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 Handwrytten operations."
    ),  
    tools=[composio_toolset],
)

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

Conclusion

You've successfully integrated Handwrytten with the Google ADK through Composio's MCP Tool Router. Your agent can now interact with Handwrytten using natural language commands.

Key takeaways:

  • The Tool Router approach dynamically routes requests to the appropriate Handwrytten 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 Handwrytten MCP Agent with another framework

FAQ

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

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

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

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

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