How to integrate Polymarket US MCP with Claude Agent SDK

This guide walks you through connecting Polymarket US to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Polymarket US agent that can list active polymarket us election markets, show your polymarket us open positions, check polymarket us market order books through natural language commands. This guide will help you understand how to give your Claude Agent SDK agent real control over a Polymarket US account through Composio's Polymarket US MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Polymarket US is the CFTC-compliant Polymarket product for verified United States users. Use it to access regulated prediction market data and account workflows through official API credentials.

44 Tools

Introduction

This guide walks you through connecting Polymarket US to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Polymarket US agent that can list active polymarket us election markets, show your polymarket us open positions, check polymarket us market order books through natural language commands.

This guide will help you understand how to give your Claude Agent SDK agent real control over a Polymarket US account through Composio's Polymarket US MCP server.

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

Also integrate Polymarket US with

OpenAI Agents SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKLangChainVercel AI SDKMastra AILlamaIndexCrewAI

TL;DR

Here's what you'll learn:
  • Get and set up your Claude/Anthropic and Composio API keys
  • Install the necessary dependencies
  • Initialize Composio and create a Tool Router session for Polymarket US
  • Configure an AI agent that can use Polymarket US as a tool
  • Run a live chat session where you can ask the agent to perform Polymarket US operations

What is Claude Agent SDK?

The Claude Agent SDK is Anthropic's official framework for building AI agents powered by Claude. It provides a streamlined interface for creating agents with MCP tool support and conversation management.

Key features include:

  • Native MCP Support: Built-in support for Model Context Protocol servers
  • Permission Modes: Control tool execution permissions
  • Streaming Responses: Real-time response streaming for interactive applications
  • Context Manager: Clean async context management for sessions

What is the Polymarket US MCP server, and what's possible with it?

The Polymarket US MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Polymarket US account. It provides structured and secure access to your markets, orders, balances, positions, and activity, so your agent can discover markets, inspect prices, place or cancel orders, and monitor your portfolio on your behalf.

  • Market and event discovery: Have your agent find Polymarket US markets, events, subjects, series, and featured topics that match your interests.
  • Price and order book research: Let the agent check the best bid and offer, review market order books, inspect market details, and look up settlement information.
  • Order creation and management: Direct your agent to place one or several live orders, review open orders, close a position, or cancel selected or all open orders.
  • Portfolio monitoring: Instruct your agent to check account balances, review current positions, and summarize trades, deposits, withdrawals, resolutions, bonuses, and transfers.
  • Sports market exploration: Have your agent browse sports, leagues, teams, and related events, including markets for leagues such as the NBA or NFL.

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

Step by step09 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Composio API Key and Claude/Anthropic API Key
  • Primary know-how of Claude Agents SDK
  • A Polymarket US account
  • Some knowledge of Python
2

Getting API Keys for Claude/Anthropic and Composio

Claude/Anthropic API Key
  • Go to the Anthropic Console and create an API key. You'll need credits to use the models.
  • 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.
3

Install dependencies

npm install @anthropic-ai/claude-agent-sdk @composio/core dotenv

Install the Composio SDK and the Claude Agents SDK.

What's happening:

  • @composio/core provides Composio integration for Anthropic
  • @anthropic-ai/claude-agent-sdk is the core agent framework
  • dotenv/config loads environment variables
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
ANTHROPIC_API_KEY=your_anthropic_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates with Composio
  • USER_ID identifies the user for session management
  • ANTHROPIC_API_KEY authenticates with Anthropic/Claude
5

Import dependencies

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

dotenv.config();
What's happening:
  • We're importing all necessary libraries including the Claude Agent SDK and Composio
  • The dotenv.config() function loads environment variables from your .env file
  • This setup prepares the foundation for connecting Claude with Polymarket US functionality
6

Create a Composio instance and Tool Router session

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

  const composio = new Composio({ apiKey: COMPOSIO_API_KEY });

  // Create Tool Router session for Polymarket US
  const session = await composio.create(USER_ID, {
    toolkits: ['polymarket_us'],
  });
  const mcpUrl = session?.mcp.url;
What's happening:
  • The function checks for the required COMPOSIO_API_KEY environment variable
  • We're creating a Composio instance using our API key
  • The create method creates a Tool Router session for Polymarket US
  • The returned url is the MCP server URL that your agent will use
7

Configure Claude Agent with MCP

const options: Options = {
  permissionMode: 'bypassPermissions',
  mcpServers: {
    composio: {
      type: 'http',
      url: mcpUrl,
      headers: { 'x-api-key': COMPOSIO_API_KEY }
    }
  },
  systemPrompt: 'You are a helpful assistant with access to Polymarket US tools via Composio.',
  maxTurns: 10,
};
What's happening:
  • We're configuring the Claude Agent options with the MCP server URL
  • permissionMode: 'bypassPermissions' allows the agent to execute operations without asking for permission each time
  • The system prompt instructs the agent that it has access to Polymarket US
  • maxTurns: 10 limits the conversation length to prevent excessive API usage
8

Create client and start chat loop

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: 'You: '
  });

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}
What's happening:
  • The readline interface is created to handle user input and output
  • The query function is used to send the user's input to the agent
  • The chat loop continues until the user types 'exit' or 'quit'
9

Run the application

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}
What's happening:
  • The chat function is the entry point for the application
  • The try-catch block is used to handle any errors that occur

Complete Code

Here's the complete code to get you started with Polymarket US and Claude Agent SDK:

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

  const composio = new Composio({ apiKey: COMPOSIO_API_KEY });
  const session = await composio.create(USER_ID, {
    toolkits: ['polymarket_us']
  });
  const mcp_url = session?.mcp.url;

  const options: Options = {
    permissionMode: 'bypassPermissions',
    mcpServers: {
      composio: {
        type: 'http',
        url: mcp_url,
        headers: { 'x-api-key': COMPOSIO_API_KEY }
      }
    },
    systemPrompt: 'You are a helpful assistant with access to Polymarket US tools via Composio.',
    maxTurns: 10,
  };

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: 'You: '
  });

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}

Conclusion

You've successfully built a Claude Agent SDK agent that can interact with Polymarket US through Composio's Tool Router.

Key features:

  • Native MCP support through Claude's agent framework
  • Streaming responses for real-time interaction
  • Permission bypass for smooth automated workflows
You can extend this by adding more toolkits, implementing custom business logic, or building a web interface around the agent.
TOOLS

Supported Tools

Every Polymarket US action and event your agent gets out of the box.

Cancel All Open Orders

Cancel all authenticated Polymarket US open orders, optionally scoped to specific market slugs.

Cancel Multiple Orders

Cancel up to 20 Polymarket US open orders in one request.

Cancel Order

Cancel one Polymarket US open order by exchange-assigned order ID.

Close Position Order

Create a live Polymarket US order intended to close an existing position in one market.

Create Multiple Orders

Submit up to 20 live Polymarket US orders in one request.

Create Order

Submit one live Polymarket US order.

Get Account Balances

Get the authenticated user's Polymarket US account balances.

Get Activities

Get authenticated Polymarket US portfolio activities such as trades, resolutions, deposits, withdrawals, referral bonuses, and transfers.

Get Event By ID

Get one Polymarket US event by numeric ID from the public gateway API.

Get Event By Slug

Get one Polymarket US event by slug from the public gateway API.

Get League By Slug

Get a current Polymarket US v2 league by slug.

Get Market BBO

Get the best bid and offer for one Polymarket US market by slug.

Get Market Book

Get the public order book for one Polymarket US market by slug.

Get Market By ID

Get one Polymarket US market by numeric ID from the public gateway API.

Get Market By Slug

Get one Polymarket US market by slug from the public gateway API.

Get Market Settlement

Get settlement information for one Polymarket US market by slug.

Get Markets For Subject

Discover Polymarket US markets associated with a subject ID.

Get Markets For Subject By Slug

Discover Polymarket US markets associated with a subject slug.

Get Open Orders

Get all open orders for the authenticated Polymarket US user.

Get Order

Get an authenticated user's Polymarket US order by exchange-assigned order ID.

Get Series By ID

Get a Polymarket US series by numeric ID.

Get Sport By Slug

Get a current Polymarket US v2 sport by slug.

Get Subject By ID

Get a Polymarket US subject entity by numeric ID.

Get Subject By Slug

Get a Polymarket US subject entity by slug.

Get Tag By ID

Get a Polymarket US topic, sport, or league tag by numeric ID.

Get Tag By Slug

Get a Polymarket US topic, sport, or league tag by slug.

Get User Positions

Get the authenticated user's Polymarket US trading positions across all markets or filtered by a specific market slug.

List Events

Discover Polymarket US events from the public gateway API.

List Events For League

List Polymarket US events for a current v2 league slug such as "nba" or "nfl".

List Events For Series

List Polymarket US sports events for a legacy v1 series ID.

List Events For Sport

List Polymarket US events for a current v2 sport slug such as "football" or "basketball".

List Featured Tags

List featured Polymarket US tag sections from the public gateway API.

List Leagues

List current Polymarket US sports leagues from the v2 public gateway API.

List Markets

Discover Polymarket US markets from the public gateway API.

List Series

List Polymarket US series from the public gateway API.

List Sports

List Polymarket US sports from the current v2 public gateway API.

List Sports Teams

List Polymarket US sports teams from the legacy v1 public gateway API.

List Sports Teams For Provider

List Polymarket US legacy v1 sports team mappings for a data provider.

List Subjects

List Polymarket US subject entities from the public gateway API.

List Tags

List ranked Polymarket US tags from the public gateway API.

Modify Multiple Orders

Modify up to 20 Polymarket US open orders in one request.

Modify Order

Modify one existing Polymarket US open order.

Preview Order

Preview a Polymarket US order without submitting it to the market.

Search Markets And Events

Search public Polymarket US markets and events for discovery.

FRAMEWORKS

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CrewAI

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FAQ

Frequently asked questions

With a standalone Polymarket US MCP server, the agents and LLMs can only access a fixed set of Polymarket US tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Polymarket US and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. Claude Agent SDK 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 Polymarket US tools.

Yes, absolutely. You can configure which Polymarket US 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.

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 Polymarket US data and credentials are handled as safely as possible.

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Co-founder, Slashy

A lot of students tell us that the moment their connected tools start talking to each other inside Opennote feels almost magical. The agent just knows them, and it's immensely helped keep new users on the platform.

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Co-founder, Opennote

We chose Composio over Pipedream because it delivered depth where it mattered — niche tools and tricky edge cases other platforms simply ignored. That gave us confidence to scale without compromising.

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As a solo builder, shipping fast is life or death. The only way I can outcompete incumbents is by outmanoeuvring them. Getting bogged down managing agent auth would have been a death sentence.

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Founder, Extra Thursday

Before Composio, adding tool integrations was slow and resource-intensive. Each one could take weeks of engineering time, and maintaining them meant constantly keeping up with API changes.

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With hands-on help from their founder, we integrated Gmail and Google Drive in just 30 minutes. This level of personal support and commitment is exactly what startups should strive for.

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