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How to integrate Postgrid MCP with Atomic Agent

Connect Atomic Agent to Postgrid MCP. Send a letter to new customer address, verify and standardize a shipping address, and more using natural language, with authentication handled for you.

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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

Atomic Agent is an open-source AI agent that runs on your machine and supports local models through llama.cpp. Connect it to 1,500+ apps through Composio, including Postgrid.

This guide uses Atomic Agent's built-in Composio integration. You need Atomic Agent v0.5.6 or later, your own Composio API key, and a Postgrid account. See the Atomic Agent documentation for installation instructions.

Also integrate Postgrid with

OpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesGoogle ADKLangChainVercel AI SDKMastra AILlamaIndexCrewAIPydantic AIAutoGen

How Atomic Agent connects to Postgrid

Atomic Agent connects to Composio's Tool Router over Streamable HTTP MCP. It discovers the tools needed for your request, and Composio handles account authentication.

Execution and account-connection tools follow Atomic Agent's configured approval policy. Review any approval prompt before allowing an action on your connected account.

Connect Postgrid to Atomic Agent

  1. Sign up or sign in to the Composio dashboard. Copy your API key.
  2. In Atomic Agent, open the Integrations tab and select Composio. Select API key, press e, paste the key, and press Enter. The tools become available immediately, without a restart.
  3. Ask Atomic Agent to do something in Postgrid. It searches Composio for the right tool.
  4. On first use, open the sign-in link returned in the chat. Connect your Postgrid account, then return to Atomic Agent to continue.

Headless setup

Add the following line to ~/.atomic-agent/.env, replacing YOUR_COMPOSIO_API_KEY with your key. Start Atomic Agent after saving the file.

bash
COMPOSIO_API_KEY=YOUR_COMPOSIO_API_KEY

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.

Use Postgrid from Atomic Agent

With your account connected, ask Atomic Agent to work with Postgrid in natural language. You can connect more apps through the same Composio integration as you need them.

Visit the Atomic Agent website or inspect the Atomic Agent source code.

Troubleshooting

Why is my API key rejected?

Copy the key directly from the Composio dashboard. Atomic Agent requires ASCII characters because it sends the key in an HTTP header. Remove any extra characters introduced when copying.

Why are Composio tools unavailable after saving a key?

Check that you use Atomic Agent v0.5.6 or later and that Composio is enabled in your configuration. A "composio": { "enabled": false } setting disables the integration while keeping the saved key on disk.

Does Composio have a free plan?

The Hobby plan includes 100,000 tool calls per month. Composio-managed OAuth apps have a lower included allowance. See Composio pricing for the current limits that apply to your connection.

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.

FRAMEWORKS

How to build Postgrid MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Postgrid MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Postgrid MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Postgrid MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Postgrid MCP with Claude Cowork

Codex logo

Codex

Use Postgrid MCP with Codex

OpenClaw logo

OpenClaw

Use Postgrid MCP with OpenClaw

Hermes logo

Hermes

Use Postgrid MCP with Hermes

Google ADK logo

Google ADK

Use Postgrid MCP with Google ADK

LangChain logo

LangChain

Use Postgrid MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Postgrid MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Postgrid MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Postgrid MCP with LlamaIndex

CrewAI logo

CrewAI

Use Postgrid MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Postgrid MCP with Pydantic AI

AutoGen logo

AutoGen

Use Postgrid MCP with AutoGen

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. Atomic Agent 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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