# How to integrate Mailbluster MCP with Pydantic AI ```json { "title": "How to integrate Mailbluster MCP with Pydantic AI", "toolkit": "Mailbluster", "toolkit_slug": "mailbluster", "framework": "Pydantic AI", "framework_slug": "pydantic-ai", "url": "https://composio.dev/toolkits/mailbluster/framework/pydantic-ai", "markdown_url": "https://composio.dev/toolkits/mailbluster/framework/pydantic-ai.md", "updated_at": "2026-05-12T10:18:05.428Z" } ``` ## Introduction This guide walks you through connecting Mailbluster to Pydantic AI using the Composio tool router. By the end, you'll have a working Mailbluster agent that can add new lead with email and name, list all products in your catalog, get details for recent order by id through natural language commands. This guide will help you understand how to give your Pydantic AI agent real control over a Mailbluster account through Composio's Mailbluster MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved. ## Also integrate Mailbluster with - [OpenAI Agents SDK](https://composio.dev/toolkits/mailbluster/framework/open-ai-agents-sdk) - [Claude Agent SDK](https://composio.dev/toolkits/mailbluster/framework/claude-agents-sdk) - [Claude Code](https://composio.dev/toolkits/mailbluster/framework/claude-code) - [Claude Cowork](https://composio.dev/toolkits/mailbluster/framework/claude-cowork) - [Codex](https://composio.dev/toolkits/mailbluster/framework/codex) - [OpenClaw](https://composio.dev/toolkits/mailbluster/framework/openclaw) - [Hermes](https://composio.dev/toolkits/mailbluster/framework/hermes-agent) - [CLI](https://composio.dev/toolkits/mailbluster/framework/cli) - [Google ADK](https://composio.dev/toolkits/mailbluster/framework/google-adk) - [LangChain](https://composio.dev/toolkits/mailbluster/framework/langchain) - [Vercel AI SDK](https://composio.dev/toolkits/mailbluster/framework/ai-sdk) - [Mastra AI](https://composio.dev/toolkits/mailbluster/framework/mastra-ai) - [LlamaIndex](https://composio.dev/toolkits/mailbluster/framework/llama-index) - [CrewAI](https://composio.dev/toolkits/mailbluster/framework/crew-ai) ## 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 Mailbluster - 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 Mailbluster 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 Mailbluster MCP server, and what's possible with it? The Mailbluster MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mailbluster account. It provides structured and secure access to your email marketing tools and data, so your agent can perform actions like creating leads, managing products, processing orders, and listing campaign resources on your behalf. - Lead creation and management: Seamlessly add new leads to your Mailbluster campaigns with just an agent prompt, ensuring your audience list stays up to date. - Product catalog management: Let your agent create, retrieve, list, or delete products in your Mailbluster catalog, making it easy to manage what you promote via email. - Order processing and tracking: Automatically create, fetch, list, or delete orders, so you always have up-to-date insights into campaign transactions and purchases. - Custom field discovery: Easily retrieve all custom fields defined in your Mailbluster account, helping your agent personalize emails or segment audiences with precision. - Bulk resource listing: Quickly list all products or orders with advanced filtering, sorting, and pagination, empowering your agent to generate tailored campaign reports or summaries. ## Supported Tools | Tool slug | Name | Description | |---|---|---| | `MAILBLUSTER_CREATE_LEAD` | Create MailBluster Lead | Tool to create a new lead in MailBluster. Use after gathering the lead's email and optional data. | | `MAILBLUSTER_CREATE_ORDER` | Create Order | Tool to create a new order in MailBluster. | | `MAILBLUSTER_CREATE_PRODUCT` | Create Product | Tool to create a new product in MailBluster. Use when you have all product details ready to add it to your MailBluster catalog. Requires a unique product ID and name. | | `MAILBLUSTER_DELETE_LEAD` | Delete MailBluster Lead | Tool to delete a lead by lead email hash. Use after confirming the lead hash (MD5 encrypted email address). | | `MAILBLUSTER_DELETE_ORDER` | Delete Order | Tool to delete a specific order. Use after confirming the order ID to remove an order from Mailbluster. | | `MAILBLUSTER_DELETE_PRODUCT` | Delete Mailbluster Product | Tool to delete a product. Use after confirming product existence. | | `MAILBLUSTER_GET_LEAD` | Get Lead | Tool to retrieve a specific lead's information using their lead hash (MD5 encrypted email address). Use when you need to fetch lead details by their email hash. | | `MAILBLUSTER_GET_ORDER` | Get Order | Tool to retrieve details of a specific order. Use when you have the order's ID. | | `MAILBLUSTER_GET_PRODUCT` | Get Product | Tool to retrieve details of a specific product. Use when you have a valid product ID and need full product information. | | `MAILBLUSTER_LIST_FIELDS` | List Fields | Tool to list all custom fields. Use when you need to retrieve all defined custom fields after authenticating with MailBluster. | | `MAILBLUSTER_LIST_ORDERS` | List Orders | Tool to list all orders. Use when you need to retrieve orders with optional pagination, sorting, or searching after authenticating with Mailbluster. | | `MAILBLUSTER_LIST_PRODUCTS` | List Products | Tool to list all products. Use when you need to retrieve products with optional pagination, sorting, or filtering. | | `MAILBLUSTER_UPDATE_LEAD` | Update MailBluster Lead | Tool to update an existing lead's information in MailBluster. Use when you need to modify lead details, subscription status, or manage tags. | | `MAILBLUSTER_UPDATE_ORDER` | Update Order | Tool to update an existing order's customer details, currency, price, and items in MailBluster. Use when you need to modify an order. | | `MAILBLUSTER_UPDATE_PRODUCT` | MailBluster Update Product | Tool to update a product in MailBluster by its ID. Use after confirming the product ID to modify attributes. | ## Supported Triggers None listed. ## Creating MCP Server - Stand-alone vs Composio SDK The Mailbluster MCP server is an implementation of the Model Context Protocol that connects your AI agent to Mailbluster. It provides structured and secure access so your agent can perform Mailbluster operations on your behalf through a secure, permission-based interface. With Composio's managed implementation, you don't have to create your own developer app. For production, if you're building an end product, we recommend using your own credentials. The managed server helps you prototype fast and go from 0-1 faster. ## Step-by-step Guide ### 1. 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 ### 1. Getting API Keys for OpenAI and Composio OpenAI API Key - Go to the [OpenAI dashboard](https://platform.openai.com/settings/organization/api-keys) 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](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs). - Navigate to your API settings and generate a new API key. - Store this key securely as you'll need it for authentication. ### 2. Install dependencies Install the required libraries. What's happening: - composio connects your agent to external SaaS tools like Mailbluster - pydantic-ai lets you create structured AI agents with tool support - python-dotenv loads your environment variables securely from a .env file ```bash pip install composio pydantic-ai python-dotenv ``` ### 3. Set up environment variables 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 ```bash COMPOSIO_API_KEY=your_composio_api_key_here USER_ID=your_user_id_here OPENAI_API_KEY=your_openai_api_key ``` ### 4. Import dependencies What's happening: - We load environment variables and import required modules - Composio manages connections to Mailbluster - MCPServerStreamableHTTP connects to the Mailbluster MCP server endpoint - Agent from Pydantic AI lets you define and run the AI assistant ```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() ``` ### 5. Create a Tool Router Session What's happening: - We're creating a Tool Router session that gives your agent access to Mailbluster 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 ```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 Mailbluster composio = Composio(api_key=api_key) session = composio.create( user_id=user_id, toolkits=["mailbluster"], ) url = session.mcp.url if not url: raise ValueError("Composio session did not return an MCP URL") ``` ### 6. Initialize the Pydantic AI Agent What's happening: - The MCP client connects to the Mailbluster endpoint - The agent uses GPT-5 to interpret user commands and perform Mailbluster operations - The instructions field defines the agent's role and behavior ```python # Attach the MCP server to a Pydantic AI Agent mailbluster_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY}) agent = Agent( "openai:gpt-5", toolsets=[mailbluster_mcp], instructions=( "You are a Mailbluster assistant. Use Mailbluster tools to help users " "with their requests. Ask clarifying questions when needed." ), ) ``` ### 7. Build the chat interface What's happening: - The agent reads input from the terminal and streams its response - Mailbluster API calls happen automatically under the hood - The model keeps conversation history to maintain context across turns ```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 Mailbluster.\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() ``` ### 8. Run the application What's happening: - The asyncio loop launches the agent and keeps it running until you exit ```python if __name__ == "__main__": asyncio.run(main()) ``` ## Complete Code ```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 Mailbluster composio = Composio(api_key=api_key) session = composio.create( user_id=user_id, toolkits=["mailbluster"], ) 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 mailbluster_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY}) agent = Agent( "openai:gpt-5", toolsets=[mailbluster_mcp], instructions=( "You are a Mailbluster assistant. Use Mailbluster 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 Mailbluster.\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 Mailbluster through Composio's Tool Router. With this setup, your agent can perform real Mailbluster 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 + Mailbluster 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 Mailbluster MCP Agent with another framework - [OpenAI Agents SDK](https://composio.dev/toolkits/mailbluster/framework/open-ai-agents-sdk) - [Claude Agent SDK](https://composio.dev/toolkits/mailbluster/framework/claude-agents-sdk) - [Claude Code](https://composio.dev/toolkits/mailbluster/framework/claude-code) - [Claude Cowork](https://composio.dev/toolkits/mailbluster/framework/claude-cowork) - [Codex](https://composio.dev/toolkits/mailbluster/framework/codex) - [OpenClaw](https://composio.dev/toolkits/mailbluster/framework/openclaw) - [Hermes](https://composio.dev/toolkits/mailbluster/framework/hermes-agent) - [CLI](https://composio.dev/toolkits/mailbluster/framework/cli) - [Google ADK](https://composio.dev/toolkits/mailbluster/framework/google-adk) - [LangChain](https://composio.dev/toolkits/mailbluster/framework/langchain) - [Vercel AI SDK](https://composio.dev/toolkits/mailbluster/framework/ai-sdk) - [Mastra AI](https://composio.dev/toolkits/mailbluster/framework/mastra-ai) - [LlamaIndex](https://composio.dev/toolkits/mailbluster/framework/llama-index) - [CrewAI](https://composio.dev/toolkits/mailbluster/framework/crew-ai) ## Related Toolkits - [Reddit](https://composio.dev/toolkits/reddit) - Reddit is a social news platform with thriving user-driven communities (subreddits). It's the go-to place for discussion, content sharing, and viral marketing. - [Facebook](https://composio.dev/toolkits/facebook) - Facebook is a social media and advertising platform for businesses and creators. It helps you connect, share, and manage content across your public Facebook Pages. - [Linkedin](https://composio.dev/toolkits/linkedin) - LinkedIn is a professional networking platform for connecting, sharing content, and engaging with business opportunities. It's the go-to place for building your professional brand and unlocking new career connections. - [Active campaign](https://composio.dev/toolkits/active_campaign) - ActiveCampaign is a marketing automation and CRM platform for managing email campaigns, sales pipelines, and customer segmentation. It helps businesses engage customers and drive growth through smart automation and targeted outreach. - [ActiveTrail](https://composio.dev/toolkits/active_trail) - ActiveTrail is a user-friendly email marketing and automation platform. It helps you reach subscribers and automate campaigns with ease. - [Ahrefs](https://composio.dev/toolkits/ahrefs) - Ahrefs is an SEO and marketing platform for site audits, keyword research, and competitor insights. It helps you improve search rankings and drive organic traffic. - [Amcards](https://composio.dev/toolkits/amcards) - AMCards lets you create and mail personalized greeting cards online. Build stronger customer relationships with easy, automated card campaigns. - [Beamer](https://composio.dev/toolkits/beamer) - Beamer is a news and changelog platform for in-app announcements and feature updates. It helps companies boost user engagement by sharing news where users are most active. - [Benchmark email](https://composio.dev/toolkits/benchmark_email) - Benchmark Email is a platform for creating, sending, and tracking email campaigns. It's built to help you engage audiences and analyze results—all in one place. - [Bigmailer](https://composio.dev/toolkits/bigmailer) - BigMailer is an email marketing platform for managing multiple brands with white-labeling and automation. It helps teams streamline campaigns and simplify integration with Amazon SES. - [Brandfetch](https://composio.dev/toolkits/brandfetch) - Brandfetch is an API that delivers company logos, colors, and visual branding assets. It helps marketers and developers keep brand visuals consistent everywhere. - [Brevo](https://composio.dev/toolkits/brevo) - Brevo is an all-in-one email and SMS marketing platform for transactional messaging, automation, and CRM. It helps businesses engage customers and streamline communications through powerful campaign tools. - [Campayn](https://composio.dev/toolkits/campayn) - Campayn is an email marketing platform for creating, sending, and managing campaigns. It helps businesses engage contacts and grow audiences with easy-to-use tools. - [Cardly](https://composio.dev/toolkits/cardly) - Cardly is a platform for creating and sending personalized direct mail to customers. It helps businesses break through the digital clutter by getting real engagement via physical mailboxes. - [ClickSend](https://composio.dev/toolkits/clicksend) - ClickSend is a cloud-based SMS and email marketing platform for businesses. It streamlines communication by enabling quick message delivery and contact management. - [Crustdata](https://composio.dev/toolkits/crustdata) - CrustData is an AI-powered data intelligence platform for real-time company and people data. It helps B2B sales teams, AI SDRs, and investors react to live business signals. - [Curated](https://composio.dev/toolkits/curated) - Curated is a platform for collecting, curating, and publishing newsletters. It streamlines content aggregation and distribution for creators and teams. - [Customerio](https://composio.dev/toolkits/customerio) - Customer.io is a customer engagement platform for targeted messaging across email, SMS, and push. Easily automate, segment, and track communications with your audience. - [Cutt ly](https://composio.dev/toolkits/cutt_ly) - Cutt.ly is a URL shortening service for managing and analyzing links. Streamline your workflows with quick, trackable, and branded short URLs. - [Demio](https://composio.dev/toolkits/demio) - Demio is webinar software built for marketers, offering both live and automated sessions with interactive features. It helps teams engage audiences and optimize lead generation through detailed analytics. ## Frequently Asked Questions ### What are the differences in Tool Router MCP and Mailbluster MCP? With a standalone Mailbluster MCP server, the agents and LLMs can only access a fixed set of Mailbluster tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Mailbluster 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 Mailbluster tools. ### Can I manage the permissions and scopes for Mailbluster while using Tool Router? Yes, absolutely. You can configure which Mailbluster 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 Mailbluster data and credentials are handled as safely as possible. --- [See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)