How to integrate Mixmax MCP with Pydantic AI

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Introduction

This guide walks you through connecting Mixmax to Pydantic AI using the Composio tool router. By the end, you'll have a working Mixmax agent that can get all mixmax emails tracked today, send a mixmax sequence to new leads, list mixmax meetings scheduled for next week through natural language commands.

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

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

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 Mixmax
  • 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 Mixmax 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 Mixmax MCP server, and what's possible with it?

The Mixmax MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mixmax account. It provides structured and secure access so your agent can perform Mixmax operations on your behalf.

Supported Tools & Triggers

Tools
Add Contact to GroupTool to add a contact to a contact group.
Add Email to Unsubscribe ListTool to add an email address to the Mixmax unsubscribe list.
Add Snippet to TagTool to add a snippet to a snippet tag in Mixmax.
Add Team MembersTool to add one or more members to a Mixmax team by email.
Cancel Sequence RecipientsTool to cancel specific recipients across all sequences.
Create Code SnippetTool to create a new Formatted Code enhancement in Mixmax.
Create ContactTool to create a new contact in Mixmax.
Create Contact GroupTool to create a new contact group in Mixmax.
Create Contact NoteTool to create a note for a contact.
Create insights reportTool to create a new insights report in Mixmax.
Create Integration EnhancementTool to create a new enhancement integration in Mixmax.
Create Integrations CommandTool to create a new slash command that will be visible to only your account.
Create Integrations SidebarsTool to create a new sidebar integration in Mixmax.
Create Link ResolverTool to create a new link resolver integration in Mixmax.
Create Livefeed SearchTool to create a new saved search in the Mixmax livefeed.
Create MessageTool to create a draft Mixmax message (email).
Create RuleTool to create a new Mixmax rule/webhook.
Create Rule ActionTool to create a new action for a Mixmax rule.
Create Sequence FolderTool to create a new sequence folder in Mixmax.
Create Snippet TagTool to create a new snippet tag (folder) in Mixmax.
Create TeamTool to create a new team in Mixmax.
Delete ContactTool to delete a contact by ID.
Delete Contact GroupTool to delete a contact group by ID.
Delete Contact NoteTool to delete a note from a contact by its ID.
Delete Integration EnhancementTool to delete an integration enhancement by its ID.
Delete slash commandTool to delete a slash command by its unique ID from Mixmax integrations.
Delete Integrations SidebarsTool to delete a sidebar integration by its ID.
Delete Link ResolverTool to permanently delete a link resolver by its ID.
Delete RuleTool to delete a Mixmax rule by its ID.
Delete Rule ActionTool to delete an action from a Mixmax rule.
Delete Sequence FolderTool to permanently delete a sequence folder by its ID.
Delete SnippetTool to delete a snippet by moving it to trash.
Delete Snippet TagTool to delete a snippet tag by its unique ID.
Delete TeamTool to delete a team by its ID.
Delete UnsubscribeTool to remove an email address from the Mixmax unsubscribe list.
Get Code SnippetTool to fetch a single Formatted Code enhancement by its unique ID.
Get contact by IDTool to retrieve a single contact by ID from Mixmax.
Get Contact GroupTool to retrieve a single contact group by ID.
Get Contactgroup ContactsTool to retrieve membership for a contact group in Mixmax.
Get Contact NotesTool to retrieve notes associated with a specific contact.
Get File RequestsTool to retrieve all file requests that you've sent out through Mixmax.
Get insights report by IDTool to retrieve a single insights report by ID from Mixmax.
Get Integrations CommandsTool to retrieve a list of Slash Commands that you have access to in Mixmax.
Get Integrations EnhancementsTool to retrieve a list of enhancements that you have access to in Mixmax.
Get Link Resolver IntegrationsTool to retrieve all link resolver integrations configured in Mixmax.
Get Integrations SidebarsTool to retrieve a list of sidebar integrations that you have access to in Mixmax.
Get live feed activity dataTool to retrieve live feed activity data from Mixmax.
Get Livefeed EventsTool to retrieve events for a specific message in the live feed.
Get Meeting InvitesTool to retrieve a paginated list of meeting invites from Mixmax.
Get Message by IDTool to retrieve a single message by its unique ID.
Get MessagesTool to retrieve messages (emails) from Mixmax.
Get PollsTool to retrieve polls created in Mixmax along with voting information.
Get Q&A SurveysTool to retrieve Question & Answer surveys data from Mixmax.
Get Reports Data TableTool to query analytics data for messages and meetings from Mixmax reports.
Get all rulesTool to retrieve all Mixmax rules for the authenticated user.
Get Rule by IDTool to fetch a single rule by its unique ID from Mixmax.
Get Salesforce account informationTool to retrieve Salesforce account information for the authenticated user.
Get Sequence Folder by IDTool to retrieve a single sequence folder by its ID from Mixmax.
Get Snippet by IDTool to fetch a single snippet by its unique ID from Mixmax.
Get Snippet TagTool to retrieve a single snippet tag (folder) by its unique ID.
Get Snippet TagsTool to retrieve a list of snippet tags (folders) from Mixmax.
Get Team MembersTool to retrieve all members of a Mixmax team.
Get TeamsTool to retrieve all teams that the authenticated user is a member of.
Get UnsubscribesTool to retrieve a list of unsubscribed email addresses from Mixmax.
Get Current User PreferencesTool to retrieve preferences for the currently authenticated user.
Get Current UserTool to retrieve information about the currently authenticated user.
Get Yes/No QuestionsTool to retrieve Yes/No questions created in Mixmax.
List Code SnippetsTool to list all Formatted Code enhancements you've created.
List Contact GroupsTool to retrieve a list of contact groups from Mixmax.
List ContactsTool to retrieve all Mixmax contacts (people you've emailed using Mixmax).
List insights reportsTool to retrieve all insights reports from Mixmax.
List Rule ActionsTool to list all actions for a given Mixmax rule.
List Sequence FoldersTool to retrieve a list of all sequence folders from Mixmax.
List SequencesTool to retrieve a list of sequences from Mixmax.
List SnippetsTool to list templates or snippets that you have access to (including those shared with you).
Update Rule by IDTool to update a rule by its unique ID in Mixmax.
Update Rule ActionTool to update an action within a Mixmax rule.
Update Snippet by IDTool to update a snippet by its unique ID in Mixmax.
Post Reports Data TableTool to generate a table report with specified analytics data for messages, meetings, or sequences.
Query ContactsTool to search for matching contacts across multiple sources including Mixmax, Google Directory, and Salesforce (contacts, leads, accounts, and opportunities).
Remove Contact from GroupTool to remove a contact from a contact group.
Remove Team MemberTool to remove a member from a Mixmax team.
Search SequencesTool to search sequence recipients by email and sequenceId from Mixmax.
Send Message DraftTool to send a message draft by its unique ID.
Send Snippet as EmailTool to send a snippet as an email to specified recipients.
Send Test MessageTool to send a test Mixmax message to the authenticated user, resolving any variables.
Update Appointment Link Calendar NameTool to update your custom "Mixmax Calendar" vanity URL name.
Update ContactTool to update a specific contact by ID.
Update Contact GroupTool to update a contact group by ID.
Update Contact NoteTool to update a note on a contact by its ID.
Update insights reportTool to update an existing insights report in Mixmax.
Update Message by IDTool to update a message by its unique ID.
Update Sequence Folder by IDTool to update a sequence folder by its unique ID in Mixmax.
Update Snippet TagTool to update a snippet tag (folder) by its unique ID.
Update TeamTool to update a team's information by ID.
Update Current User PreferencesTool to update preferences for the currently authenticated user.

What is the Composio tool router, and how does it fit here?

What is Tool Router?

Composio's Tool Router 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 Tool Router

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Tool Router works

The Tool Router 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 Mixmax
  • 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 Mixmax
  • MCPServerStreamableHTTP connects to the Mixmax 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 Mixmax
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["mixmax"],
    )
    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 Mixmax 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
mixmax_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
agent = Agent(
    "openai:gpt-5",
    toolsets=[mixmax_mcp],
    instructions=(
        "You are a Mixmax assistant. Use Mixmax tools to help users "
        "with their requests. Ask clarifying questions when needed."
    ),
)
What's happening:
  • The MCP client connects to the Mixmax endpoint
  • The agent uses GPT-5 to interpret user commands and perform Mixmax 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 Mixmax.\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
  • Mixmax 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 Mixmax 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 Mixmax
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["mixmax"],
    )
    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
    mixmax_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[mixmax_mcp],
        instructions=(
            "You are a Mixmax assistant. Use Mixmax 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 Mixmax.\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 Mixmax through Composio's Tool Router. With this setup, your agent can perform real Mixmax 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 + Mixmax 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 Mixmax MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Mixmax MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Mixmax MCP with Claude Agent SDK

Google ADK

Google ADK

Use Mixmax MCP with Google ADK

LangChain

LangChain

Use Mixmax MCP with LangChain

Vercel AI SDK

Vercel AI SDK

Use Mixmax MCP with Vercel AI SDK

Mastra AI

Mastra AI

Use Mixmax MCP with Mastra AI

LlamaIndex

LlamaIndex

Use Mixmax MCP with LlamaIndex

CrewAI

CrewAI

Use Mixmax MCP with CrewAI

Claude Code

Claude Code

Use Mixmax MCP with Claude Code

Codex

Codex

Use Mixmax MCP with Codex

FAQ

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

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

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

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

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