How to integrate Holded MCP with Google ADK

This guide walks you through connecting Holded to Google ADK using the Composio tool router. By the end, you'll have a working Holded agent that can create invoices, find your invoices, update contacts, delete invoices, and review contact details through natural language commands. This guide will help you understand how to give your Google ADK agent real control over a Holded account through Composio's Holded MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Holded

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Holded is business management software for invoices, sales documents, services, contacts, groups, and tags. It helps teams keep finance and customer operations organized in one place.

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Introduction

This guide will help you understand how to give your Google ADK agent real control over a Holded account through Composio's Holded MCP server.

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

Also integrate Holded with

OpenAI Agents SDK Claude Agent SDK Claude Code Claude Cowork Codex OpenClaw Hermes CLI LangChain Vercel AI SDK Mastra AI LlamaIndex CrewAI

TL;DR

Here's what you'll learn:

Get a Holded account set up and connected to Composio
Install the Google ADK and Composio packages
Create a Composio Tool Router session for Holded
Build an agent that connects to Holded through MCP
Interact with Holded 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 Holded MCP server, and what's possible with it?

The Holded MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Holded account. It provides structured and secure access to your contacts and sales invoices, so your agent can find, create, review, update, and delete business records on your behalf.

Contact creation and management: Have your agent create customers, suppliers, leads, debtors, or creditors, then update selected details as they change.
Contact search and review: Instruct your agent to find contacts by name, email, phone number, tax information, or external reference and retrieve their complete profiles.
Sales invoice creation: Let the agent create sales invoices for existing contacts with the required line items and details.
Invoice tracking and review: Direct your agent to find invoices by document number, contact, payment status, issue date, or due date and review their lines, totals, and payment summaries.
Record updates and cleanup: Have your agent update selected invoice fields or permanently delete contacts and invoices you no longer need.

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:

Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Step by step09 STEPS

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 Holded 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=["holded"],
)

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 Holded 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 Holded 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=["holded"],
)

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

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

Conclusion

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

Key takeaways:

The Tool Router approach dynamically routes requests to the appropriate Holded 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.

TOOLS

Supported Tools

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

Create Contact

Create a customer, supplier, lead, debtor, creditor, or unclassified contact and return its new Holded ID.

Create Invoice

Create a sales invoice for an existing contact and return its ID; this does not send, approve, or record payment for the invoice.

Delete Contact

Permanently delete one contact by ID; linked documents keep display text but lose the live contact association.

Delete Invoice

Permanently delete one invoice and its recorded payments; its document number is not reused.

Find Contacts

Find Holded contacts by name prefix or an exact email, phone, mobile, tax ID, or external ID.

Find Invoices

Find Holded invoices by fuzzy document-number prefix or list them by contact, payment status, issue date, or due date.

Get Contact

Return the complete profile of one contact by its Holded contact ID.

Get Invoice

Return full details, lines, totals, and payment summary for one invoice by its Holded ID.

Update Contact

Safely change selected fields on a contact without clearing unspecified profile data.

Update Invoice

Safely change selected mutable fields on an invoice without clearing unspecified invoice data or altering recorded payments.

FRAMEWORKS

How to build Holded MCP Agent with another framework

OpenAI Agents SDK

Use Holded MCP with OpenAI Agents SDK

Claude Agent SDK

Use Holded MCP with Claude Agent SDK

Claude Code

Use Holded MCP with Claude Code

Claude Cowork

Use Holded MCP with Claude Cowork

Codex

Use Holded MCP with Codex

OpenClaw

Use Holded MCP with OpenClaw

Hermes

Use Holded MCP with Hermes

CLI

Use Holded MCP with CLI

LangChain

Use Holded MCP with LangChain

Vercel AI SDK

Use Holded MCP with Vercel AI SDK

Mastra AI

Use Holded MCP with Mastra AI

LlamaIndex

Use Holded MCP with LlamaIndex

CrewAI

Use Holded MCP with CrewAI

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FAQ

Frequently asked questions

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

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 Holded tools.

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

Start with Holded.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Holded tool your agent needs.Free to start.

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Customer stories

Teams ship real agents on Composio

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Karan skipped his own birthday party to fix our critical issue. It was 10pm and he diverted his Waymo to help us instead. This really sets the bar — it shows the commitment you need when users rely on your software.

Harsha Gaddipati

Co-founder, Slashy

A lot of students tell us that the moment their connected tools start talking to each other inside Opennote feels almost magical. The agent just knows them, and it's immensely helped keep new users on the platform.

Abhi Arya

Co-founder, Opennote

We chose Composio over Pipedream because it delivered depth where it mattered — niche tools and tricky edge cases other platforms simply ignored. That gave us confidence to scale without compromising.

Nirman Dave

CEO, Zams

As a solo builder, shipping fast is life or death. The only way I can outcompete incumbents is by outmanoeuvring them. Getting bogged down managing agent auth would have been a death sentence.

Ryan Yu

Founder, Extra Thursday

Before Composio, adding tool integrations was slow and resource-intensive. Each one could take weeks of engineering time, and maintaining them meant constantly keeping up with API changes.

Tomisin Jenrola

Founder & CEO, SwarmZero

With hands-on help from their founder, we integrated Gmail and Google Drive in just 30 minutes. This level of personal support and commitment is exactly what startups should strive for.

Jerome Leclanche

Co-Founder, Ingram Technologies

How to integrate Holded MCP with Google ADK

Connect Holded without auth hassles

Introduction

Also integrate Holded with

TL;DR

What is Google ADK?

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

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

What is Composio SDK?

How the Composio SDK works

Step-by-step Guide

Prerequisites

Getting API Keys for Google and Composio

Install dependencies

Set up ADK project

Set environment variables

Import modules and validate environment

Create Composio client and Tool Router session

Set up the McpToolset and create the Agent

Run the agent

Complete Code

Conclusion

Supported Tools

How to build Holded MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

LangChain

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

44API

Alpaca

Billsby

Brex

Frequently asked questions

What are the differences in Tool Router MCP and Holded MCP?+

Can I use Tool Router MCP with Google ADK?+

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

How safe is my data with Composio Tool Router?+

Start with Holded.It takes 30 seconds.

Teams ship real agents on Composio