How to integrate Postgrid MCP with Claude Code

Manage your Postgrid 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

Postgrid logoPostgrid
Api Key

Postgrid is an API platform for automating direct mail and address verification. It helps businesses send mail and verify addresses instantly, reducing manual effort and errors.

60 Tools

Introduction

Manage your Postgrid 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 Postgrid 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 Postgrid 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 Postgrid MCP server, and what's possible with it?

The Postgrid MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Postgrid account. It provides structured and secure access to your direct mail and address automation tools, so your agent can verify addresses, send letters, manage contacts, and handle templates for your business communications—all without manual intervention.

  • Automated letter sending: Have your agent create and send physical letters on demand, handling recipient, sender, and content details seamlessly.
  • Contact management: Effortlessly add, update, or delete contacts in your Postgrid account to keep your mailing lists accurate and up to date.
  • Template creation and maintenance: Let your agent generate reusable mail templates with dynamic placeholders, and remove outdated templates as needed.
  • Bank account and payment management: Create or delete bank accounts associated with print and mail services, ensuring smooth financial operations for mail automation.
  • Webhook setup and monitoring: Enable your agent to create or remove webhooks to track events and receive real-time notifications for your mail orders and services.

Connecting Postgrid 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 Postgrid) 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 Postgrid 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: ['postgrid'],
});

const composioMcpUrl = composioSession?.mcp.url;

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

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

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 Postgrid
  • 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 Postgrid MCP to Claude Code

bash
claude mcp add --transport http postgrid-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 (postgrid-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 Postgrid MCP server is properly configured.

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

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

Claude Code MCP list showing the toolkit MCP server
10

Authenticate Postgrid

The first time you try to use Postgrid tools, you'll be prompted to authenticate.

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

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

  • "Send a letter to new customer address"
  • "Verify and standardize a shipping address"
  • "Create a reusable postcard template"

Complete Code

Here's the complete code to get you started with Postgrid 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: ['postgrid'],
});

const composioMcpUrl = composioSession?.mcp.url;

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

Conclusion

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

Key features of this setup:

  • Terminal-native experience without switching contexts
  • Natural language commands for Postgrid 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 Postgrid 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 Postgrid action and event your agent gets out of the box.

Cancel Box

Tool to cancel a box order by its ID.

Cancel Cheque

Tool to cancel a cheque order by its ID.

Cancel Cheque with Note

Tool to cancel a cheque order with a cancellation note.

Cancel Postcard

Tool to cancel a postcard order.

Cancel Postcard With Note

Tool to cancel a postcard order with an optional cancellation note.

Cancel Return Envelope Order

Tool to cancel a return envelope order.

CREATE_BANK_ACCOUNT

Tool to create a new bank account for print & mail service.

Create Box

Tool to create a box mailing order for letters with plastic cards or cheques.

Create Cheque

Tool to create a cheque order for physical cheque mailing.

Create Contact

Tool to create a new contact in PostGrid.

Create Letter

Tool to create and send a letter via PostGrid.

Create Postcard

Tool to create and send a postcard via PostGrid.

Create Return Envelope

Tool to create a return envelope for mail recipients to respond.

Create Return Envelope Order

Tool to create a batch order of return envelopes to be printed and delivered.

Create Template

Tool to create a new mail template in PostGrid.

Create Template Editor Session

Tool to create a template editor session for interactive template editing.

Create Tracker

Tool to create a tracker for monitoring mail delivery status via URL tracking.

Create Webhook

Tool to create a new webhook to receive order event notifications.

Delete Bank Account

Tool to delete a bank account by its ID.

Delete Contact

Tool to delete a contact by its ID.

Delete Template

Tool to delete a template by its ID.

Delete Template Editor Session

Tool to delete a template editor session by its ID.

Delete Tracker

Tool to delete a tracker by its ID.

Delete Webhook

Tool to delete a webhook subscription.

Fill Test Return Envelope Order

Tool to fill a test return envelope order for testing purposes.

Get Bank Account

Tool to retrieve a bank account.

Get Box

Tool to retrieve a specific box order by ID.

Get Cheque

Tool to retrieve a specific cheque by ID.

Get Contact

Tool to retrieve a contact.

Get Letter

Tool to retrieve a letter.

Get Postcard

Tool to retrieve a specific postcard by ID.

Get Return Envelope

Tool to retrieve a return envelope.

Get Return Envelope Order

Tool to retrieve a specific return envelope order.

Get Template

Tool to retrieve a template.

Get Tracker

Tool to retrieve a tracker.

Get Webhook

Tool to retrieve details of a specific webhook by its ID.

List Bank Accounts

Tool to list bank accounts.

List Box Orders

Tool to list box orders.

List Cheques

Tool to list cheques with optional filters and pagination.

List Contacts

Tool to list contacts.

List Webhook Events

Tool to retrieve a list of webhook events with optional pagination.

List Letters

Tool to list letters.

List Postal Statements

Tool to list all postal statements for billing and tracking purposes.

List Postcards

Tool to retrieve a list of postcards with optional filtering and pagination.

List Return Envelope Orders

Tool to list all return envelope orders for a specific return envelope.

List Return Envelopes

Tool to list return envelopes.

List Self-Mailers

Tool to list self-mailers.

List Sub-Organizations

Tool to list sub-organizations.

List Template Editor Sessions

Tool to list template editor sessions.

List Templates

Tool to list templates.

List Trackers

Tool to list all trackers.

List Tracker Visits

Tool to list all visits for a tracker.

List Webhook Invocations

Tool to list previous invocations of a webhook with response status codes.

List Webhooks

Tool to retrieve a list of configured webhooks with optional filtering and pagination.

Progress Test Box

Tool to progress a test box through processing stages for webhook testing.

Progress Test Cheque

Tool to progress a test cheque through processing stages for webhook testing.

Progress Test Postcard

Tool to progress a test postcard through processing stages for webhook testing.

Update Template

Tool to update an existing mail template in PostGrid.

Update Tracker

Tool to update an existing tracker's redirect URL template and/or expiration settings.

Update Webhook

Tool to update an existing webhook configuration.

FAQ

Frequently asked questions

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

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

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