How to integrate Etermin MCP with Pydantic AI

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Introduction

This guide walks you through connecting Etermin to Pydantic AI using the Composio tool router. By the end, you'll have a working Etermin agent that can add new client contact for booking, remove canceled appointment from calendar, create voucher for returning customer through natural language commands.

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

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

Also integrate Etermin 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 Etermin
  • 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 Etermin 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 Etermin MCP server, and what's possible with it?

The Etermin MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Etermin account. It provides structured and secure access to your appointment scheduling system, so your agent can perform actions like creating contacts, managing bookings, updating resources, and handling calendar events on your behalf.

  • Automated contact and user creation: Instantly add new clients or team members to your Etermin account, streamlining onboarding and customer management.
  • Effortless appointment and calendar management: Let your agent delete existing appointments or calendars, freeing up schedules and reducing manual work.
  • Resource and service administration: Automatically create or remove resources and services, ensuring your booking system stays current as your business evolves.
  • Voucher and webhook setup: Quickly generate new vouchers for promotions or set up webhooks for real-time event notifications and integrations.
  • Contact and service deletion: Easily remove outdated contacts or services, keeping your scheduling platform organized and clutter-free.

Supported Tools & Triggers

Tools
Assign Calendar ServiceTool to assign a service to a calendar in eTermin.
Create AbsenceTool to create an absence (non-working time) for a specific calendar.
Create AnchortimeTool to create anchortimes (recurring time slots) in a calendar.
Create Anchortime by DateTool to create anchortimes by date.
Create AppointmentTool to create a new appointment in eTermin.
Create Appointment via SyncTool to create an appointment via sync in eTermin.
Create Calendar Return TimeTool to create a return time for a calendar.
Create ContactTool to create a new contact in eTermin.
Create ServiceTool to create a new service in eTermin.
Create Service GroupTool to create a new service group in eTermin.
Create UserTool to create a new user.
Create UsermappingTool to create a new usermapping in eTermin.
Create VoucherCreates a new discount voucher in eTermin.
Create WebhookCreates a webhook (web push notification) in eTermin to receive real-time updates about appointments.
Create Working TimeTool to create a new working time slot in eTermin.
Create Working Times DateTool to create a working times date slot for a calendar.
Delete AbsenceTool to delete an absence (non-working time) from a calendar.
Delete AnchortimeDelete an anchortime from eTermin by its ID.
Delete Anchortime By DateDelete an anchortime by date using its ID.
Delete AppointmentDelete an existing appointment by its ID.
Delete Appointment via SyncTool to delete appointments via the sync endpoint.
Delete CalendarDelete a calendar from your eTermin account.
Delete Calendar Return TimeDelete a return time from a calendar.
Delete Calendar ServiceDelete an assigned service from a calendar in eTermin.
Delete ContactDelete a contact from your eTermin account by its contact ID.
Delete ResourceDelete an eTermin resource by type and ID.
Delete ServicePermanently deletes a service from your eTermin account by its ID.
Delete Service GroupDelete a service group from your eTermin account by its ID.
Delete UserDeletes an existing user from the eTermin account.
Delete UsermappingDelete a usermapping by its ID.
Delete VoucherPermanently deletes a voucher from eTermin by its voucher code.
Delete WebhookDelete an existing webhook by its unique identifier.
Delete Working TimesTool to delete working times from a calendar.
Delete Working Times DateTool to delete working times date entries from eTermin.
Get AbsencesTool to retrieve absences (non-working times) for a specific calendar.
Get Anchortime by DateTool to retrieve anchortimes by date.
Get AnchortimesTool to retrieve anchortime details.
Get Appointment SyncTool to synchronize appointments incrementally from eTermin.
Get Bookingpage LogsTool to retrieve bookingpage request logs from eTermin.
Get Calendar Return TimeTool to retrieve return times for a specific calendar.
Get CalendarsTool to retrieve calendars.
Get Calendar Service AssignmentsTool to retrieve calendar service assignments.
Get CompanyTool to retrieve company account details.
Get Contact By IDTool to retrieve a specific contact by ID, external ID, or email.
Get ContactsTool to retrieve a list of contacts.
Get Deleted AppointmentsTool to retrieve a list of deleted appointments from eTermin.
Get Message LogsTool to retrieve message logs from eTermin.
Get Customer RatingsTool to retrieve a list of customer ratings from eTermin.
Get Service By IDTool to retrieve a specific service from eTermin.
Get Service CalendarTool to retrieve calendars for a specific service ID.
Get Service GroupTool to retrieve service group details from eTermin.
Get ServicesTool to retrieve a list of services.
Get Survey ResultsTool to retrieve survey results from eTermin.
Get TimeslotsTool to retrieve available timeslots for a specific calendar on a given date.
Get UsermappingTool to retrieve usermapping information.
Get UsersTool to retrieve a list of users.
Get Working TimesTool to retrieve working times for a specific calendar.
Get Working Times DateTool to retrieve working times for a specific calendar on a specific date.
List AppointmentsTool to retrieve a filtered list of appointments from eTermin in a specified date range.
List VouchersRetrieve all vouchers (discount codes) from your eTermin account.
List WebhooksTool to retrieve webhooks.
Update Service via PUTTool to update a service in eTermin.
Update AbsenceTool to update an absence (non-working time) for a calendar in eTermin.
Update AnchortimeUpdate an existing anchortime in eTermin.
Update Anchortime By DateTool to update anchortimes by date in eTermin.
Update AppointmentTool to update an existing appointment in eTermin.
Update CalendarUpdate an existing calendar in eTermin.
Update Calendar Return TimeTool to update a return time for a calendar in eTermin.
Update ContactTool to update an existing contact in eTermin.
Update ResourceUpdate an existing eTermin resource (contact, service, calendar, user, or voucher).
Update ServiceTool to update an existing service.
Update Service GroupTool to update an existing service group in eTermin.
Update Synchronised AppointmentTool to update a synchronised appointment in eTermin.
Update UsermappingUpdate an existing usermapping in eTermin.
Update VoucherUpdates an existing voucher in eTermin.
Update WebhookUpdate an existing webhook configuration in eTermin.
Update Working TimesTool to update working times for a calendar in eTermin.
Update Working Times DateTool to update working times date for a calendar.

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 Etermin
  • 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 Etermin
  • MCPServerStreamableHTTP connects to the Etermin 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 Etermin
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["etermin"],
    )
    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 Etermin 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
etermin_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
agent = Agent(
    "openai:gpt-5",
    toolsets=[etermin_mcp],
    instructions=(
        "You are a Etermin assistant. Use Etermin tools to help users "
        "with their requests. Ask clarifying questions when needed."
    ),
)
What's happening:
  • The MCP client connects to the Etermin endpoint
  • The agent uses GPT-5 to interpret user commands and perform Etermin 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 Etermin.\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
  • Etermin 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 Etermin 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 Etermin
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["etermin"],
    )
    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
    etermin_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[etermin_mcp],
        instructions=(
            "You are a Etermin assistant. Use Etermin 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 Etermin.\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 Etermin through Composio's Tool Router. With this setup, your agent can perform real Etermin 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 + Etermin for workflow automation)
This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations.

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FAQ

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

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

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

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

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