How to integrate Polygon MCP with Pydantic AI

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Introduction

This guide walks you through connecting Polygon to Pydantic AI using the Composio tool router. By the end, you'll have a working Polygon agent that can show the latest closing price for btc-usd, list all stock tickers traded on nasdaq, get the crypto rsi for eth over 14 days through natural language commands.

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

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

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

The Polygon MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Polygon account. It provides structured and secure access to real-time and historical financial market data, so your agent can retrieve market status, analyze price indicators, track dividends, and monitor crypto and stock tickers on your behalf.

  • Market status and holiday tracking: Instantly check if U.S. exchanges are open or closed and retrieve upcoming market holidays or early closures to plan trading activities.
  • Comprehensive ticker retrieval: Ask your agent to fetch all available ticker symbols across asset classes, including stocks, crypto, forex, and options, filtered by market or exchange.
  • Crypto technical analysis: Have your agent calculate moving averages (EMA, SMA), MACD, and RSI indicators for specific cryptocurrencies to support informed trading decisions.
  • Daily and historical price fetching: Let your agent retrieve daily open/close prices, previous day’s close, or detailed price history for cryptocurrencies and stocks with just a prompt.
  • Dividend data extraction: Effortlessly access up-to-date corporate dividend information for stocks, enabling portfolio reviews and income analysis.

Supported Tools & Triggers

Tools
Get 10-K Filing SectionsTool to retrieve 10-K filing sections from the SEC.
Get AggregatesTool to fetch custom aggregate OHLCV bars for a stock.
Get All TickersTool to retrieve all ticker symbols across asset classes.
Get Condition CodesTool to retrieve a unified list of trade and quote condition codes and their definitions.
Get Crypto AggregatesTool to retrieve aggregate bars for a cryptocurrency over a time range.
Get Crypto All Tickers SnapshotTool to retrieve snapshots for all cryptocurrency tickers.
Get Crypto EMATool to calculate Exponential Moving Average (EMA) technical indicator for a crypto ticker.
Get Crypto Grouped DailyTool to retrieve daily grouped bars for all cryptocurrencies on a specified date.
Get Crypto Last TradeTool to retrieve the last trade for a specified cryptocurrency pair.
Get Crypto MACDTool to calculate Moving Average Convergence/Divergence (MACD) technical indicator for a crypto ticker.
Get Crypto Open/CloseTool to fetch daily open and close prices for a given crypto pair on a specified date.
Get Crypto Previous CloseTool to retrieve previous day’s close for a crypto ticker.
Get Crypto RSITool to calculate the Relative Strength Index (RSI) for a cryptocurrency ticker.
Get Crypto SMATool to calculate Simple Moving Average (SMA) technical indicator for a cryptocurrency ticker.
Get Crypto Ticker BookTool to retrieve the full L2 order book for a crypto ticker.
Get Crypto TradesTool to fetch historical trade data for a cryptocurrency ticker.
Get DividendsTool to retrieve dividend data for stocks.
Get Economy Inflation IndicatorsTool to retrieve key indicators of realized inflation including CPI and PCE price indexes.
Get Exponential Moving AverageTool to retrieve the Exponential Moving Average for a stock ticker.
Get SEC FilingTool to retrieve SEC filing details by filing ID.
Get SEC Filing FileTool to retrieve information about a specific SEC filing file.
Get Forex AggregatesTool to retrieve aggregate bars for a forex pair over a date range.
Get Forex EMATool to calculate Exponential Moving Average (EMA) technical indicator for a forex pair.
Get Forex Grouped Daily BarsTool to retrieve daily grouped OHLC bars for all forex currency pairs on a specified date.
Get Forex Historical QuotesTool to retrieve historical forex quotes for a currency pair over a time range.
Get Forex LocalesTool to list locales supported by Polygon's forex asset class.
Get Forex MACDTool to calculate Moving Average Convergence/Divergence (MACD) technical indicator for a forex pair.
Get Forex Previous CloseTool to retrieve previous day's close for a forex ticker.
Get Forex Real-Time Currency ConversionTool to convert amounts between currency pairs using real-time forex rates.
Get Forex RSITool to calculate the Relative Strength Index (RSI) technical indicator for a forex pair.
Get Forex SMATool to calculate Simple Moving Average (SMA) technical indicator for a forex pair.
Get Forex Snapshot LosersTool to retrieve the current snapshot of the top losers in the forex market.
Get Futures AggregatesTool to retrieve historical OHLCV aggregates for a futures contract.
Get Futures ProductsTool to retrieve a comprehensive list of futures products with advanced filtering.
Get Futures Product SchedulesTool to retrieve trading schedules for a futures product.
Get Futures QuotesTool to retrieve real-time quote data for a specified futures contract ticker.
Get Futures SchedulesTool to retrieve futures trading schedules.
Get Futures TradesTool to retrieve tick-level trade data for a specified futures contract.
Get Historic Forex TicksTool to get historic ticks for a currency pair on a specific date.
Get Inflation ExpectationsTool to retrieve inflation expectations data from the Federal Reserve based on Treasury yields and Cleveland Fed models.
Get IPO DataTool to retrieve comprehensive information on Initial Public Offerings (IPOs), including upcoming and historical events.
Get MACDTool to retrieve the Moving Average Convergence/Divergence (MACD) for a stock ticker.
Get Upcoming Market HolidaysTool to retrieve upcoming market holidays and half-day closures.
Get Market StatusTool to retrieve current market status.
Get Meta Conditions By TicktypeTool to retrieve condition code mappings for a specific tick type (trades or quotes).
Get NewsTool to retrieve recent news articles related to a ticker.
Get Stock Open/CloseTool to fetch daily open and close prices for a stock on a specific date.
Get Option Chain SnapshotTool to fetch a real-time snapshot of all option contracts for an underlying asset.
Get Options Contract OverviewTool to retrieve comprehensive details about a specific options contract including contract type, exercise style, expiration date, strike price, and underlying ticker.
Get Options Custom BarsTool to retrieve historical OHLC and volume data for options contracts over custom date ranges with configurable time windows.
Get Options EMATool to calculate Exponential Moving Average (EMA) technical indicator for an options ticker.
Get Options MACDTool to calculate Moving Average Convergence/Divergence (MACD) technical indicator for an options ticker.
Get Option SnapshotTool to retrieve a real-time snapshot for a single option contract.
Get Options RSITool to calculate Relative Strength Index (RSI) technical indicator for an options ticker.
Get Options SMATool to calculate Simple Moving Average (SMA) technical indicator for an options ticker.
Get Previous CloseTool to get previous trading day’s OHLC and volume for a stock.
Get reference exchangesTool to retrieve supported exchanges and their details.
Get reference marketsTool to retrieve all supported markets from Polygon.
Get Reference Ticker TypesTool to retrieve all ticker types supported by Polygon.
Get Related CompaniesTool to get a list of related companies for a ticker symbol based on various similarity metrics.
Get Risk CategoriesTool to retrieve risk factor taxonomy categories from SEC 10-K filings.
Get RSITool to retrieve the Relative Strength Index (RSI) for a stock ticker.
Get Short InterestTool to retrieve bi-monthly aggregated short interest data for stocks reported to FINRA.
Get Short VolumeTool to retrieve short volume data for stocks.
Get Simple Moving AverageTool to retrieve the Simple Moving Average (SMA) for any ticker (stocks, forex, crypto).
Get All Stock Tickers SnapshotTool to retrieve the current market snapshot for all stock tickers.
Get Stock Snapshot LosersTool to retrieve the current snapshot of the top losers in the U.
Get Stock Snapshot TickerTool to retrieve the current snapshot of a specific stock ticker.
Get Stock SplitsTool to retrieve stock split events.
Get Stock FinancialsTool to retrieve historical financial data for a stock ticker from SEC filings.
Get Stock FloatTool to retrieve stock float data showing the number and percentage of publicly tradable shares.
Get Stocks Balance SheetsTool to retrieve point-in-time balance sheet data including assets, liabilities, and equity from company SEC filings.
Get Stocks Cash Flow StatementsTool to retrieve historical cash flow statement data from company SEC filings across quarterly, annual, and TTM frequencies.
Get Stocks Custom BarsTool to retrieve aggregated historical OHLC and volume data for a stock over custom date ranges with configurable time windows.
Get Stocks Daily Market SummaryTool to retrieve daily OHLC, volume, and VWAP data for all U.
Get Stock Splits by TickerTool to retrieve historical stock splits for a specific ticker symbol.
Get Simple Moving Average (SMA)Tool to fetch Simple Moving Average (SMA) for a given stock ticker.
Get Ticker Company DetailsTool to retrieve detailed company information for a stock ticker.
Get Ticker DetailsTool to retrieve detailed information for a ticker.
Get Ticker Details (vX)Tool to retrieve comprehensive details for a specific ticker symbol using Polygon's vX API.
Get Ticker EventsTool to retrieve corporate events for a specific ticker.
Get Ticker TypesTool to retrieve all ticker types supported by Polygon.
Get Treasury YieldsTool to retrieve historical U.
Get V1 Meta Crypto ExchangesTool to retrieve a list of cryptocurrency exchanges using the legacy v1 API.
Last Quote for a SymbolTool to retrieve the last quote tick for a given stock symbol.
Last Trade for a Currency PairTool to retrieve the last trade tick for a currency pair in the forex market.
List SEC Filing FilesTool to retrieve files associated with an SEC filing.
List Options ContractsTool to list and filter options contracts by underlying ticker, type, expiration, strike, and more.
List SEC FilingsTool to retrieve SEC filings from Polygon.

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

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

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

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

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