How to integrate Alchemy MCP with Pydantic AI

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Introduction

This guide walks you through connecting Alchemy to Pydantic AI using the Composio tool router. By the end, you'll have a working Alchemy agent that can show all nfts owned by this wallet, get recent sales for a specific nft collection, check erc20 token balances for your address through natural language commands.

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

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

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

The Alchemy MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Alchemy account. It provides structured and secure access to your blockchain data, so your agent can perform actions like fetching NFT metadata, tracking token balances, analyzing transaction history, and managing Ethereum assets on your behalf.

  • Retrieve NFT contract and token metadata: Instantly access detailed information about any NFT collection or token, including name, symbol, supply, and contract deployer.
  • Analyze NFT sales and ownership: Let your agent fetch historical NFT sales across marketplaces and list current owners for any ERC-721 or ERC-1155 token.
  • Track token balances and portfolio: Effortlessly check ERC-20 token balances for any Ethereum address to monitor holdings or build portfolio analytics.
  • List NFTs within a collection: Pull a complete list of NFTs under a specific contract to explore, display, or analyze full collections.
  • Monitor transaction counts and activity: Quickly get the transaction count (nonce) for any Ethereum address to understand activity or prepare for new transactions.

Supported Tools & Triggers

Tools
Compute NFT RarityTool to compute the rarity of each attribute for a specific NFT based on its collection.
Get NFT Collection MetadataTool to get metadata for an NFT collection using its marketplace slug (OpenSea, LooksRare, etc).
Get Collections for OwnerTool to retrieve all NFT collections held by a specified owner address.
Get Contract Metadata Batch V3Tool to retrieve metadata for multiple NFT contracts in a single batch request.
Get Contract Metadata V3Tool to get the metadata for an NFT contract including name, symbol, total supply, and token type (ERC721/ERC1155).
Get Contracts for Owner (NFT API v3)Tool to get all NFT contracts owned by an address with contract metadata.
Get NFT Floor PriceTool to get the floor price for an NFT collection across multiple marketplaces (OpenSea, LooksRare, etc).
Get Historical Token PricesRetrieves historical price data for a token over a specified time range with configurable intervals.
Get NFT Contracts By AddressTool to retrieve NFT contracts associated with one or more wallet addresses across multiple blockchain networks.
Get NFT MetadataTool to retrieve comprehensive metadata for a specific NFT, including contract details, media URLs, attributes, ownership info, and OpenSea data.
Get NFT Metadata BatchTool to retrieve metadata for multiple NFTs in a single request (up to 100 NFTs), including contract details, media URLs, attributes, and collection data.
Get NFT Sales V3Retrieves NFT sales that have occurred through on-chain marketplaces using Alchemy's v3 API.
Get NFTs for Collection V3Retrieves all NFTs in a collection using OpenSea collection slug or contract address.
Get NFTs for ContractRetrieves all NFTs for a given NFT contract address.
Get NFTs for OwnerTool to get all NFTs currently owned by a given address.
Get Owners for CollectionTool to retrieve all owner addresses for a given NFT collection contract.
Get Owners for ContractTool to get all owners of NFTs in a contract with optional token balances.
Get NFT Owners (v3)Tool to retrieve all owners for a specific NFT using Alchemy's v3 API.
Get Portfolio NFTs By AddressTool to fetch NFTs owned by multiple wallet addresses across different blockchain networks.
Get Token Prices By SymbolTool to get current token prices by symbol (e.
Get Token BalancesThis tool retrieves ERC20 token balances for a specified Ethereum address.
Get Token Balances By AddressTool to get token balances for wallet addresses across multiple networks using Alchemy's Portfolio API.
Get Token MetadataRetrieves metadata for an ERC-20 token on Ethereum mainnet, including its name, symbol, decimals, and logo URL.
Get Token Prices By AddressRetrieves current token prices by contract address and network from decentralized exchanges (DEXes).
Get Tokens By AddressTool to fetch fungible tokens (native, ERC-20, SPL) for multiple wallet addresses across networks.
Get Transaction CountThis tool retrieves the number of transactions sent from a specific address (also known as the nonce).
Get Transactions History By AddressTool to get transaction history for wallet addresses across multiple networks using Alchemy's Data API.
Invalidate NFT Contract CacheTool to invalidate the cached metadata for an NFT contract.
Check If NFT Is AirdropTool to check if a specific NFT token is marked as an airdrop.
Check If NFT Is AirdropTool to determine whether an NFT was airdropped to the owner address.
Check Collection OwnershipTool to check if a wallet address owns any token from a specific NFT collection.
Check NFT Holder StatusTool to check if a wallet address holds any NFTs from a specific contract.
Check if Contract is SpamTool to check if an NFT contract is marked as spam by Alchemy.
Check if Contract is Spam (V3)Tool to determine if a specific NFT contract is marked as spam by Alchemy.
Search NFT Contract MetadataTool to search for keywords across metadata of all ERC-721 and ERC-1155 smart contracts.
Summarize NFT AttributesRetrieves a comprehensive summary of all attributes and traits for NFTs in a collection, including trait counts and distribution statistics.

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

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

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

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

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