How to integrate Customerio MCP with Pydantic AI

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Introduction

This guide walks you through connecting Customerio to Pydantic AI using the Composio tool router. By the end, you'll have a working Customerio agent that can list all segments in your workspace, get delivery metrics for last week's emails, show all people in vip customer segment through natural language commands.

This guide will help you understand how to give your Pydantic AI agent real control over a Customerio account through Composio's Customerio MCP server.

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

Also integrate Customerio with

TL;DR

Here's what you'll learn:
  • How to set up your Composio API key and User ID
  • How to create a Composio Tool Router session for Customerio
  • How to attach an MCP Server to a Pydantic AI agent
  • How to stream responses and maintain chat history
  • How to build a simple REPL-style chat interface to test your Customerio workflows

What is Pydantic AI?

Pydantic AI is a Python framework for building AI agents with strong typing and validation. It leverages Pydantic's data validation capabilities to create robust, type-safe AI applications.

Key features include:

  • Type Safety: Built on Pydantic for automatic data validation
  • MCP Support: Native support for Model Context Protocol servers
  • Streaming: Built-in support for streaming responses
  • Async First: Designed for async/await patterns

What is the Customerio MCP server, and what's possible with it?

The Customerio MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Customer.io account. It provides structured and secure access to your customer engagement workspace, allowing your agent to send targeted communications, manage segments, retrieve messaging analytics, and automate customer data management on your behalf.

  • Targeted message analytics and tracking: Retrieve detailed lists of messages sent, including delivery metrics, to monitor campaign performance and engagement.
  • Segment discovery and membership management: Let your agent fetch all segments, get details for a specific segment, and list all customers in a segment for precise audience targeting.
  • Integration and webhook management: Have your agent list and review all integrations and webhooks in your workspace to streamline system connectivity and reporting.
  • Customer profile suppression: Direct your agent to permanently suppress (delete and block) customer profiles, ensuring compliance and data privacy.
  • Collection metadata retrieval: Retrieve up-to-date details for all collections in your workspace, keeping your AI-powered workflows and automations in sync with your data sources.

Supported Tools & Triggers

Tools
Suppress Customer ProfileTool to suppress a person.
Get IntegrationsTool to retrieve a list of integrations in your workspace.
Get MessagesTool to retrieve a list of messages sent from your workspace.
Get Segment DetailsTool to retrieve details of a specific segment.
Get Segment MembershipTool to retrieve people in a specific segment.
Get SegmentsTool to retrieve a list of segments in your workspace.
Get TriggerTool to retrieve details about a specific trigger.
Get TriggersTool to retrieve a list of triggers for a specific broadcast.
Get Customer.io Workspace WebhooksTool to retrieve a list of webhooks.
List CollectionsTool to list all collections metadata.
List NewslettersTool to list all newsletters.
List SnippetsTool to list all snippets in your workspace.
List Transactional MessagesTool to list all transactional message templates.
Trigger BroadcastTool to manually trigger a broadcast.

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

Prerequisites

Before starting, make sure you have:
  • Python 3.9 or higher
  • A Composio account with an active API key
  • Basic familiarity with Python and async programming

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.

Install dependencies

bash
pip install composio pydantic-ai python-dotenv

Install the required libraries.

What's happening:

  • composio connects your agent to external SaaS tools like Customerio
  • pydantic-ai lets you create structured AI agents with tool support
  • python-dotenv loads your environment variables securely from a .env file

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your agent to Composio's API
  • USER_ID associates your session with your account for secure tool access
  • OPENAI_API_KEY to access OpenAI LLMs

Import dependencies

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()
What's happening:
  • We load environment variables and import required modules
  • Composio manages connections to Customerio
  • MCPServerStreamableHTTP connects to the Customerio MCP server endpoint
  • Agent from Pydantic AI lets you define and run the AI assistant

Create a Tool Router Session

python
async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for Customerio
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["customerio"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")
What's happening:
  • We're creating a Tool Router session that gives your agent access to Customerio tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned session.mcp.url is the MCP server URL that your agent will use

Initialize the Pydantic AI Agent

python
# Attach the MCP server to a Pydantic AI Agent
customerio_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
agent = Agent(
    "openai:gpt-5",
    toolsets=[customerio_mcp],
    instructions=(
        "You are a Customerio assistant. Use Customerio tools to help users "
        "with their requests. Ask clarifying questions when needed."
    ),
)
What's happening:
  • The MCP client connects to the Customerio endpoint
  • The agent uses GPT-5 to interpret user commands and perform Customerio operations
  • The instructions field defines the agent's role and behavior

Build the chat interface

python
# Simple REPL with message history
history = []
print("Chat started! Type 'exit' or 'quit' to end.\n")
print("Try asking the agent to help you with Customerio.\n")

while True:
    user_input = input("You: ").strip()
    if user_input.lower() in {"exit", "quit", "bye"}:
        print("\nGoodbye!")
        break
    if not user_input:
        continue

    print("\nAgent is thinking...\n", flush=True)

    async with agent.run_stream(user_input, message_history=history) as stream_result:
        collected_text = ""
        async for chunk in stream_result.stream_output():
            text_piece = None
            if isinstance(chunk, str):
                text_piece = chunk
            elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                text_piece = chunk.delta
            elif hasattr(chunk, "text"):
                text_piece = chunk.text
            if text_piece:
                collected_text += text_piece
        result = stream_result

    print(f"Agent: {collected_text}\n")
    history = result.all_messages()
What's happening:
  • The agent reads input from the terminal and streams its response
  • Customerio API calls happen automatically under the hood
  • The model keeps conversation history to maintain context across turns

Run the application

python
if __name__ == "__main__":
    asyncio.run(main())
What's happening:
  • The asyncio loop launches the agent and keeps it running until you exit

Complete Code

Here's the complete code to get you started with Customerio and Pydantic AI:

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()

async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for Customerio
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["customerio"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")

    # Attach the MCP server to a Pydantic AI Agent
    customerio_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[customerio_mcp],
        instructions=(
            "You are a Customerio assistant. Use Customerio tools to help users "
            "with their requests. Ask clarifying questions when needed."
        ),
    )

    # Simple REPL with message history
    history = []
    print("Chat started! Type 'exit' or 'quit' to end.\n")
    print("Try asking the agent to help you with Customerio.\n")

    while True:
        user_input = input("You: ").strip()
        if user_input.lower() in {"exit", "quit", "bye"}:
            print("\nGoodbye!")
            break
        if not user_input:
            continue

        print("\nAgent is thinking...\n", flush=True)

        async with agent.run_stream(user_input, message_history=history) as stream_result:
            collected_text = ""
            async for chunk in stream_result.stream_output():
                text_piece = None
                if isinstance(chunk, str):
                    text_piece = chunk
                elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                    text_piece = chunk.delta
                elif hasattr(chunk, "text"):
                    text_piece = chunk.text
                if text_piece:
                    collected_text += text_piece
            result = stream_result

        print(f"Agent: {collected_text}\n")
        history = result.all_messages()

if __name__ == "__main__":
    asyncio.run(main())

Conclusion

You've built a Pydantic AI agent that can interact with Customerio through Composio's Tool Router. With this setup, your agent can perform real Customerio actions through natural language. You can extend this further by:
  • Adding other toolkits like Gmail, HubSpot, or Salesforce
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows (for example, Gmail + Customerio for workflow automation)
This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations.

How to build Customerio MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Customerio MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Customerio MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Customerio MCP with Claude Code

Codex logo

Codex

Use Customerio MCP with Codex

OpenClaw logo

OpenClaw

Use Customerio MCP with OpenClaw

CLI logo

CLI

Use Customerio MCP with CLI

Google ADK logo

Google ADK

Use Customerio MCP with Google ADK

LangChain logo

LangChain

Use Customerio MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Customerio MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Customerio MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Customerio MCP with LlamaIndex

CrewAI logo

CrewAI

Use Customerio MCP with CrewAI

FAQ

What are the differences in Tool Router MCP and Customerio MCP?

With a standalone Customerio MCP server, the agents and LLMs can only access a fixed set of Customerio tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Customerio and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with Pydantic AI?

Yes, you can. Pydantic AI 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 Customerio tools.

Can I manage the permissions and scopes for Customerio while using Tool Router?

Yes, absolutely. You can configure which Customerio 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.

How safe is my data with Composio Tool Router?

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 Customerio data and credentials are handled as safely as possible.

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