How to integrate Billsby MCP with Google ADK

This guide walks you through connecting Billsby to Google ADK using the Composio tool router. By the end, you'll have a working Billsby agent that can list active subscriptions expiring this month, find overdue invoices by customer, update allowance for enterprise plan through natural language commands. This guide will help you understand how to give your Google ADK agent real control over a Billsby account through Composio's Billsby MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Billsby is a subscription billing platform for managing customers, subscriptions, invoices, products, plans, usage counters, add-ons, and allowances. It helps SaaS and subscription teams automate billing operations without building complex billing logic from scratch.

10 Tools

Introduction

This guide walks you through connecting Billsby to Google ADK using the Composio tool router. By the end, you'll have a working Billsby agent that can list active subscriptions expiring this month, find overdue invoices by customer, update allowance for enterprise plan through natural language commands.

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

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

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OpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLILangChainVercel AI SDKMastra AILlamaIndexCrewAI

TL;DR

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

The Billsby MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Billsby account. It provides structured and secure access to your customers, subscriptions, products, plans, and billing details, so your agent can create and update customers, review subscriptions, browse products and plans, check shipping addresses, and monitor billing information on your behalf.

  • Customer creation and updates: Have your agent create customers without subscriptions or payment cards, then update their contact and billing address details when needed.
  • Customer account lookup: Let the agent retrieve a customer’s billing, contact, payment status, and account details, or find customers by a partial name.
  • Subscription review: Direct your agent to list subscriptions and review their billing schedules, status, customer, product, plan, pricing, trial, and revenue details.
  • Product and plan discovery: Instruct your agent to browse products by name or visibility and review the plans and billing cycles available for each product.
  • Subscription shipping details: Have your agent retrieve the shipping address associated with a subscription when you need to confirm delivery information.

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:

  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

Step by step09 STEPS
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
2

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.
3

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 Billsby via MCP
  • python-dotenv loads environment variables
4

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
5

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
6

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
7

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=["billsby"],
)

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
8

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 Billsby 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
9

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 Billsby 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=["billsby"],
)

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

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

Conclusion

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

Key takeaways:

  • The Tool Router approach dynamically routes requests to the appropriate Billsby 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 Billsby action and event your agent gets out of the box.

Create Customer

Create a Billsby customer without a subscription or payment card.

Get Customer

Get billing, contact, payment-status, and account details for one Billsby customer.

Get Subscription

Get billing schedule, customer, product, plan, pricing, status, and revenue details for one Billsby subscription.

Get Subscription Shipping Address

Get the shipping address associated with one Billsby subscription.

List Customers

Return one page of customers for the connected Billsby company, optionally filtered by a partial customer name.

List Customer Subscriptions

List all subscriptions belonging to one Billsby customer.

List Product Plans

List the plans and billing cycles configured for one Billsby product.

List Products

Return one page of Billsby products, optionally filtered by name or visibility.

List Subscriptions

Return one page of company subscriptions with optional status, trial, product, plan, and ordering filters.

Update Customer

Replace the editable contact and billing-address details for an existing Billsby customer.

FRAMEWORKS

How to build Billsby MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Billsby MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Billsby MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Billsby MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Billsby MCP with Claude Cowork

Codex logo

Codex

Use Billsby MCP with Codex

OpenClaw logo

OpenClaw

Use Billsby MCP with OpenClaw

Hermes logo

Hermes

Use Billsby MCP with Hermes

CLI logo

CLI

Use Billsby MCP with CLI

LangChain logo

LangChain

Use Billsby MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Billsby MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Billsby MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Billsby MCP with LlamaIndex

CrewAI logo

CrewAI

Use Billsby MCP with CrewAI

FAQ

Frequently asked questions

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

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

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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.

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