How to integrate Postal Data API MCP with Claude Code

Manage your Postal Data API directly from Claude Code with zero worries about OAuth hassles, API-breaking issues, or reliability and security concerns. You can do this in two different ways: Via Composio Connect - Direct and easiest approach Via Composio SDK - Programmatic approach with more control

Postal Data API logoPostal 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.

6 Tools

Introduction

Manage your Postal Data API directly from Claude Code with zero worries about OAuth hassles, API-breaking issues, or reliability and security concerns.

You can do this in two different ways:

  1. Via Composio Connect - Direct and easiest approach
  2. Via Composio SDK - Programmatic approach with more control

Also integrate Postal Data API with

Why use Composio?

  • Only one MCP URL to connect multiple apps with Claude Code with zero auth hassles.
  • Programmatic tool calling allows LLMs to write its code in a remote workbench to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
  • Handling Large tool responses out of LLM context to minimize context rot.
  • Dynamic just-in-time access to 20,000 tools across 1000+ other Apps for cross-app workflows. It loads the tools you need, so LLMs aren't overwhelmed by tools you don't need.

Connecting Postal Data API to Claude Code using Composio

1. Add the Composio MCP to Claude

Terminal

2. Start Claude Code

bash
claude

3. Open your MCP list

bash
/mcp

4. Select Composio and click on Authenticate

Select Composio and click Authenticate

5. This will redirect you to the Composio OAuth page. Complete the flow by authorizing Composio and you're all set.

Composio OAuth authorization page
Composio authorization complete
Ask Claude to connect to your account and authenticate via the link

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.

Connecting Postal Data API via Composio SDK

Composio SDK is the underlying tech that powers Rube. It's a universal gateway that does everything Rube does but with much more programmatic control. You can programmatically generate an MCP URL with the app you need (here Postal Data API) for even more tool search precision. It's secure and reliable.

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 step10 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Claude Pro, Max, or API billing enabled Anthropic account
  • Composio API Key
  • A Postal Data API account
  • Basic knowledge of Python or TypeScript
2

Install Claude Code

bash
# macOS, Linux, WSL
curl -fsSL https://claude.ai/install.sh | bash

# Windows PowerShell
irm https://claude.ai/install.ps1 | iex

# Windows CMD
curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd && del install.cmd

To install Claude Code, use one of the following methods based on your operating system:

3

Set up Claude Code

bash
cd your-project-folder
claude

Open a terminal, go to your project folder, and start Claude Code:

  • Claude Code will open in your terminal
  • Follow the prompts to sign in with your Anthropic account
  • Complete the authentication flow
  • Once authenticated, you can start using Claude Code
Claude Code initial setup showing sign-in prompt
Claude Code terminal after successful login
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here

Create a .env file in your project root with the following variables:

  • COMPOSIO_API_KEY authenticates with Composio (get it from Composio dashboard)
  • USER_ID identifies the user for session management (use any unique identifier)
5

Install Composio library

npm install @composio/core dotenv

Install the Composio TypeScript library to create MCP sessions.

  • @composio/core provides the core Composio functionality
  • dotenv loads environment variables from your .env file
6

Generate Composio MCP URL

import 'dotenv/config';
import { Composio } from '@composio/core';

const { COMPOSIO_API_KEY, USER_ID } = process.env;

if (!COMPOSIO_API_KEY || !USER_ID) {
  throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}

const composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['postal_data_api'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http postal_data_api-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Create a script to generate a Composio MCP URL for Postal Data API. This URL will be used to connect Claude Code to Postal Data API.

What's happening

  • We import the Composio client and load environment variables
  • Create a Composio instance with your API key
  • Call create() to create a Tool Router session for Postal Data API
  • The returned mcp.url is the MCP server URL that Claude Code will use
  • The script prints this URL so you can copy it
7

Run the script and copy the MCP URL

node --loader ts-node/esm generate_mcp_url.ts
# or if using tsx
tsx generate_mcp_url.ts

Run your TypeScript script to generate the MCP URL.

  • The script connects to Composio and creates a Tool Router session
  • It prints the MCP URL and the exact command you need to run
  • Copy the entire claude mcp add command from the output
8

Add Postal Data API MCP to Claude Code

bash
claude mcp add --transport http postal_data_api-composio "YOUR_MCP_URL_HERE" --headers "X-API-Key:YOUR_COMPOSIO_API_KEY"

# Then restart Claude Code
exit
claude

In your terminal, add the MCP server using the command from the previous step. The command format is:

  • claude mcp add registers a new MCP server with Claude Code
  • --transport http specifies that this is an HTTP-based MCP server
  • The server name (postal_data_api-composio) is how you'll reference it
  • The URL points to your Composio Tool Router session
  • --headers includes your Composio API key for authentication

After running the command, close the current Claude Code session and start a new one for the changes to take effect.

9

Verify the installation

bash
claude mcp list

Check that your Postal Data API MCP server is properly configured.

  • This command lists all MCP servers registered with Claude Code
  • You should see your postal_data_api-composio entry in the list
  • This confirms that Claude Code can now access Postal Data API tools

If everything is wired up, you should see your postal_data_api-composio entry listed:

Claude Code MCP list showing the toolkit MCP server
10

Authenticate Postal Data API

The first time you try to use Postal Data API tools, you'll be prompted to authenticate.

  • Claude Code will detect that you need to authenticate with Postal Data API
  • It will show you an authentication link
  • Open the link in your browser (or copy/paste it)
  • Complete the Postal Data API authorization flow
  • Return to the terminal and start using Postal Data API through Claude Code

Once authenticated, you can ask Claude Code to perform Postal Data API operations in natural language. For example:

  • "Validate ZIP code for customer address"
  • "Find coordinates for postal code"
  • "Lookup region metadata by postcode"

Complete Code

Here's the complete code to get you started with Postal Data API and Claude Code:

import 'dotenv/config';
import { Composio } from '@composio/core';

const { COMPOSIO_API_KEY, USER_ID } = process.env;

if (!COMPOSIO_API_KEY || !USER_ID) {
  throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}

const composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['postal_data_api'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http postal_data_api-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Conclusion

You've successfully integrated Postal Data API with Claude Code using Composio's MCP server. Now you can interact with Postal Data API directly from your terminal using natural language commands.

Key features of this setup:

  • Terminal-native experience without switching contexts
  • Natural language commands for Postal Data API operations
  • Secure authentication through Composio's managed MCP
  • Tool Router for dynamic tool discovery and execution

Next steps:

  • Try asking Claude Code to perform various Postal Data API operations
  • Add more toolkits to your Tool Router session for multi-app workflows
  • Integrate this setup into your development workflow for increased productivity

You can extend this by adding more toolkits, implementing custom workflows, or building automation scripts that leverage Claude Code's capabilities.

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.

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. Claude Code 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.

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