How to integrate Postal Data API MCP with Google ADK

This guide walks you through connecting Postal Data API to Google ADK using the Composio tool router. By the end, you'll have a working Postal Data API agent that can look up postal codes, validate your postal codes, search by city, and get location metadata through natural language commands. This guide will help you understand how to give your Google ADK agent real control over a Postal Data API account through Composio's Postal Data API MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Postal Data API

Api Key

Postal Data API is a global postal code validation and lookup service. Use it to verify locations, coordinates, and regional data across 240+ countries.

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Introduction

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

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

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

The Postal Data API MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Postal Data API account. It provides structured and secure access to global postal code and location data, so your agent can validate postal codes, look up locations and coordinates, search postal codes by city, retrieve regional metadata, and check service information on your behalf.

Postal code validation: Have your agent check whether a postal code exists without treating an invalid code as an execution error.
Bulk postal code checks: Instruct your agent to validate up to 1,000 postal codes at once, including codes from different countries.
Location and coordinate lookup: Let the agent find the city, region, and coordinates associated with a postal code.
City-based postal code search: Direct your agent to find postal codes for a city and optional region, including close matches.
Regional details and service status: Have your agent retrieve available timezone, county, elevation, and administrative details for a postal code, or check coverage, guidance, balance, and rate-limit status.

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 Postal Data API 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=["postal_data_api"],
)

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 Postal Data API 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 Postal Data API 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=["postal_data_api"],
)

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 Postal Data API operations."
    ),  
    tools=[composio_toolset],
)

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

Conclusion

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

Key takeaways:

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

Get API Information

Return Postal Data API version, coverage, usage guidance, current balance, and configured rate-limit status when returned, for connectivity or service discovery.

Get Postal Code Metadata

Return all available country-specific metadata for a postal code, such as coordinates, timezone, county, elevation, and administrative levels.

Look Up Postal Code

Look up the city, region, and coordinates for a postal code.

Search Postal Codes by City

Return all postal codes matching a city and optional region, including fuzzy-match details.

Validate Postal Code

Check whether one postal code exists without treating a nonexistent code as an execution error.

Validate Postal Codes in Bulk

Validate 1 to 1,000 postal codes synchronously, including mixed-country batches.

FRAMEWORKS

How to build Postal Data API MCP Agent with another framework

OpenAI Agents SDK

Use Postal Data API MCP with OpenAI Agents SDK

Claude Agent SDK

Use Postal Data API MCP with Claude Agent SDK

Claude Code

Use Postal Data API MCP with Claude Code

Claude Cowork

Use Postal Data API MCP with Claude Cowork

Codex

Use Postal Data API MCP with Codex

OpenClaw

Use Postal Data API MCP with OpenClaw

Hermes

Use Postal Data API MCP with Hermes

CLI

Use Postal Data API MCP with CLI

LangChain

Use Postal Data API MCP with LangChain

Vercel AI SDK

Use Postal Data API MCP with Vercel AI SDK

Mastra AI

Use Postal Data API MCP with Mastra AI

LlamaIndex

Use Postal Data API MCP with LlamaIndex

CrewAI

Use Postal Data API MCP with CrewAI

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FAQ

Frequently asked questions

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

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

Start with Postal Data API.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Postal Data API 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 Postal Data API MCP with Google ADK

Connect Postal Data API without auth hassles

Introduction

Also integrate Postal Data API with

TL;DR

What is Google ADK?

What is the Postal Data API 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 Postal Data API 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

Excel

Adafruit IO

Agenty

ApexVerify

Frequently asked questions

What are the differences in Tool Router MCP and Postal Data API MCP?+

Can I use Tool Router MCP with Google ADK?+

Can I manage the permissions and scopes for Postal Data API while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Postal Data API.It takes 30 seconds.

Teams ship real agents on Composio