How to integrate Beaconchain MCP with Pydantic AI

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Introduction

This guide walks you through connecting Beaconchain to Pydantic AI using the Composio tool router. By the end, you'll have a working Beaconchain agent that can check if your ethereum node is syncing, get health status of the beacon chain node, fetch details for validator id 12345 through natural language commands.

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

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

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

The Beaconchain MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Beaconchain account. It provides structured and secure access to Ethereum 2.0 Beacon Chain analytics, so your agent can check validator status, monitor node health, analyze network performance, and surface real-time blockchain insights on your behalf.

  • Validator information lookup: Instantly retrieve in-depth details about any specific Ethereum 2.0 validator, including performance, status, and rewards.
  • Node health monitoring: Let your agent check the real-time health status of your node, including readiness, syncing state, and error conditions.
  • Network performance insights: Surface up-to-date statistics on the overall Beacon Chain network, empowering you to make informed decisions.
  • Automated health alerts: Have your agent proactively monitor node status and notify you if any issues or anomalies arise.

Supported Tools & Triggers

Tools
Get ChartRetrieve chart visualizations from beaconcha.
Get EpochRetrieve aggregate metrics and status for a beacon chain epoch.
Get ETH1 Deposits by Transaction HashRetrieve all beacon chain validator deposit events associated with a specific execution-layer transaction hash.
Get ETH.Store Daily AggregatesRetrieve ETH.
Get ERC-20 Token BalancesRetrieve a paginated list of ERC-20 token balances for a specific Ethereum address.
Get Execution BlockRetrieve one or more execution-layer blocks by block number from the Ethereum Beacon Chain.
Get Execution Produced BlocksRetrieve execution-layer blocks attributed to one or more producers.
Get Latest StateRetrieve the latest known Ethereum Beacon Chain network state.
Get Network PerformanceRetrieve aggregated network performance metrics for the Ethereum Beacon Chain.
Get Explorer HealthCheck the health status of the beaconcha.
Get Validator QueuesRetrieve current queue metrics for Ethereum Beacon Chain validators.
Get Rocket Pool ValidatorRetrieve Rocket Pool-specific metadata for validators including minipool status, node fee, smoothing pool status, and RPL stake metrics.
Get SlotRetrieve detailed information about an Ethereum Beacon Chain slot.
Get Slot AttestationsRetrieve all attestations included in the beacon block for a specific slot.
Get Slot Attester SlashingsRetrieve all attester slashing operations included in the beacon block for a specific slot.
Get Slot Proposer SlashingsRetrieve all proposer slashing operations included in the beacon block for a specific slot.
Get Slot Voluntary ExitsRetrieve all voluntary exit operations included in the beacon block for a specific slot.
Get Sync CommitteeRetrieve the sync committee membership for a given sync period.
Get ValidatorRetrieve detailed information about an Ethereum Beacon Chain validator.
Get Validator Attestation EfficiencyRetrieve normalized attestation inclusion effectiveness for one or more validators.
Get Validator AttestationsRetrieve attestations observed for one or more validators within a bounded epoch window.
Get Validator Balance HistoryRetrieve per-epoch balance history for one or more Ethereum Beacon Chain validators.
Get Validator BLS ChangesRetrieve on-chain BLS-to-execution credential change messages (EIP-4881) for validators.
Get Validator Consensus RewardsRetrieve consensus-layer rewards for one or more validators over multiple lookback windows.
Get Validator Daily StatsRetrieve per-day statistics for a single Ethereum Beacon Chain validator by index.
Get Validator DepositsRetrieve execution-layer deposit events for one or more validators.
Get Validator Execution RewardsRetrieve execution-layer rewards (priority fees and MEV payments) for one or more validators.
Get Validator Income HistoryRetrieve a per-epoch income breakdown for one or more validators.
Get Validator LeaderboardRetrieve the current top 100 validators ranked by 7-day consensus-layer rewards.
Get Validator ProposalsRetrieve beacon chain blocks proposed by one or more validators within a bounded epoch window.
Get Validators by Deposit AddressRetrieve validators that have made deposits from a specific execution-layer address.
Get Validators by Withdrawal CredentialsRetrieve validators whose withdrawal credentials match the provided value or execution-layer address.
Get Validators Proposal LuckRetrieve proposal luck statistics for one or more Ethereum Beacon Chain validators.
Get Validators QueueRetrieve current queue metrics for validators on the Ethereum Beacon Chain.
Get Validator WithdrawalsRetrieve withdrawal operations attributed to one or more validators within a bounded epoch window.
Post ValidatorsRetrieve validator information using a JSON request body for multiple validators.
Resolve ENS Name or AddressResolve ENS (Ethereum Name Service) names to addresses and vice versa.

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

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

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

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

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