How to integrate Open sea MCP with Claude Agent SDK

This guide walks you through connecting Open sea to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Open sea agent that can list your nft for sale on opensea, show all active listings in bored ape collection, create an offer for a specific cryptopunk through natural language commands. This guide will help you understand how to give your Claude Agent SDK agent real control over a Open sea account through Composio's Open sea MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Open sea

Api Key

OpenSea is the world's first and largest NFT marketplace for digital collectibles and crypto assets. Instantly buy, sell, and explore NFTs across blockchains, all in one place.

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Introduction

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

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

Also integrate Open sea with

OpenAI Agents SDK Claude Code Claude Cowork Codex OpenClaw Hermes CLI Google ADK LangChain Vercel AI SDK Mastra AI LlamaIndex CrewAI

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 Open sea
Configure an AI agent that can use Open sea as a tool
Run a live chat session where you can ask the agent to perform Open sea 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 Open sea MCP server, and what's possible with it?

The Open sea MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your OpenSea account. It provides structured and secure access to your NFT marketplace activity, so your agent can perform actions like listing NFTs for sale, creating and fulfilling offers, checking account details, and managing your marketplace orders on your behalf.

NFT listing automation: Quickly list any ERC721 or ERC1155 NFT for sale on OpenSea, specifying price and collection details—all handled by your agent.
Offer creation and management: Instruct your agent to create criteria-based or single-item offers to purchase specific NFTs or those matching certain traits within a collection.
Order and listing fulfillment: Let your agent retrieve all necessary information and signatures to fulfill existing listings or offers, making transactions seamless and secure.
Marketplace activity insights: Have the agent pull your profile details, fetch all active listings or offers for a given collection, and provide you with up-to-date marketplace snapshots.
Order cancellation and management: Direct your agent to cancel open orders, listings, or offers off-chain, helping you stay in control of your marketplace participation with ease.

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:

Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Step by step09 STEPS

Prerequisites

Before starting, make sure you have:

Composio API Key and Claude/Anthropic API Key
Primary know-how of Claude Agents SDK
A Open sea account
Some knowledge of Python

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.

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

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

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 Open sea functionality

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 Open sea
  const session = await composio.create(USER_ID, {
    toolkits: ['open_sea'],
  });
  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 Open sea
The returned url is the MCP server URL that your agent will use

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 Open sea 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 Open sea
maxTurns: 10 limits the conversation length to prevent excessive API usage

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'

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 Open sea 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: ['open_sea']
  });
  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 Open sea 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 Open sea 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 Open sea action and event your agent gets out of the box.

Build criteria offer

Build a portion of a criteria offer including the merkle tree needed to post an offer.

Cancel order

Offchain cancel a single order, offer or listing, by its order hash when protected by the SignedZone.

Create criteria offer

Create a criteria offer to purchase any NFT in a collection or which matches the specified trait.

Create item offer

Create an offer to purchase a single NFT (ERC721 or ERC1155).

Create listing

List a single NFT (ERC721 or ERC1155) for sale on the OpenSea marketplace.

Fulfill listing

Retrieve all the information, including signatures, needed to fulfill a listing directly onchain.

Fulfill offer

Retrieve all the information, including signatures, needed to fulfill an offer directly onchain.

Get account

Get an OpenSea Account Profile including details such as bio, social media usernames, and profile image.

Get all listings by collection

Get all active, valid listings for a single collection.

Get all offers by collection

Get all active, valid offers for the specified collection.

Get best listing by nft

Get the best listing for an NFT.

Get best listings by collection

Get the cheapest priced active, valid listings on a single collection.

Get best offer by nft

Get the best offers for an NFT.

Get collection

Get a single collection including details such as fees, traits, and links.

Get collections

Get a list of OpenSea collections with optional filtering and pagination.

Get collection stats

Get stats for a single collection on OpenSea.

Get contract

Get a smart contract for a given chain and address.

Get events

Get a list of events from OpenSea based on various filters like timestamps and event types.

Get listings

Get the complete set of active, valid listings.

Get nft

Get metadata, traits, ownership information, and rarity for a single NFT.

Get order

Get a single order, offer or listing, by its order hash.

Get payment token

Get a smart contract for a given chain and address.

Get traits

Get the traits in a collection.

Refresh nft metadata

Refresh metadata for a single NFT.

FRAMEWORKS

How to build Open sea MCP Agent with another framework

OpenAI Agents SDK

Use Open sea MCP with OpenAI Agents SDK

Claude Code

Use Open sea MCP with Claude Code

Claude Cowork

Use Open sea MCP with Claude Cowork

Codex

Use Open sea MCP with Codex

OpenClaw

Use Open sea MCP with OpenClaw

Hermes

Use Open sea MCP with Hermes

CLI

Use Open sea MCP with CLI

Google ADK

Use Open sea MCP with Google ADK

LangChain

Use Open sea MCP with LangChain

Vercel AI SDK

Use Open sea MCP with Vercel AI SDK

Mastra AI

Use Open sea MCP with Mastra AI

LlamaIndex

Use Open sea MCP with LlamaIndex

CrewAI

Use Open sea MCP with CrewAI

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Addresszen

Api Key

Addresszen is a real-time address autocomplete and verification service. It helps capture accurate, deliverable addresses with instant suggestions and validation.

Asin data api

Api Key

Asin data api gives you detailed, real-time product data from Amazon, including price, rank, and reviews. Perfect for e-commerce pros and data-driven marketers who need instant marketplace insights.

Baselinker

Api Key

BaseLinker is an all-in-one e-commerce management platform connecting stores, marketplaces, carriers, and more. It streamlines order processing, inventory control, and automates your sales operations.

Bestbuy

Api Key

Best Buy is a leading retailer offering APIs for product, store, and recommendation data. Instantly access up-to-date retail insights for smarter shopping and decision-making.

FAQ

Frequently asked questions

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

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

Start with Open sea.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Open sea tool your agent needs.Free to start.

Start building

Customer stories

Teams ship real agents on Composio

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Karan skipped his own birthday party to fix our critical issue. It was 10pm and he diverted his Waymo to help us instead. This really sets the bar — it shows the commitment you need when users rely on your software.

Harsha Gaddipati

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.

Abhi Arya

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.

Nirman Dave

CEO, Zams

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.

Ryan Yu

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.

Tomisin Jenrola

Founder & CEO, SwarmZero

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.

Jerome Leclanche

Co-Founder, Ingram Technologies

How to integrate Open sea MCP with Claude Agent SDK

Connect Open sea without auth hassles

Introduction

Also integrate Open sea with

TL;DR

What is Claude Agent SDK?

What is the Open sea MCP server, and what's possible with it?

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

How the Composio SDK works

Step-by-step Guide

Prerequisites

Getting API Keys for Claude/Anthropic and Composio

Install dependencies

Set up environment variables

Import dependencies

Create a Composio instance and Tool Router session

Configure Claude Agent with MCP

Create client and start chat loop

Run the application

Complete Code

Conclusion

Supported Tools

How to build Open sea MCP Agent with another framework

OpenAI Agents SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

LangChain

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

Addresszen

Asin data api

Baselinker

Bestbuy

Frequently asked questions

What are the differences in Tool Router MCP and Open sea MCP?+

Can I use Tool Router MCP with Claude Agent SDK?+

Can I manage the permissions and scopes for Open sea while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Open sea.It takes 30 seconds.

Teams ship real agents on Composio