# How to integrate Blocknative MCP with LangChain

```json
{
  "title": "How to integrate Blocknative MCP with LangChain",
  "toolkit": "Blocknative",
  "toolkit_slug": "blocknative",
  "framework": "LangChain",
  "framework_slug": "langchain",
  "url": "https://composio.dev/toolkits/blocknative/framework/langchain",
  "markdown_url": "https://composio.dev/toolkits/blocknative/framework/langchain.md",
  "updated_at": "2026-05-12T10:03:23.260Z"
}
```

## Introduction

This guide walks you through connecting Blocknative to LangChain using the Composio tool router. By the end, you'll have a working Blocknative agent that can monitor transaction status for a given hash, fetch current ethereum gas price distribution, list all supported blockchains for monitoring through natural language commands.
This guide will help you understand how to give your LangChain agent real control over a Blocknative account through Composio's Blocknative MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.

## Also integrate Blocknative with

- [OpenAI Agents SDK](https://composio.dev/toolkits/blocknative/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/blocknative/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/blocknative/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/blocknative/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/blocknative/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/blocknative/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/blocknative/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/blocknative/framework/cli)
- [Google ADK](https://composio.dev/toolkits/blocknative/framework/google-adk)
- [Vercel AI SDK](https://composio.dev/toolkits/blocknative/framework/ai-sdk)
- [Mastra AI](https://composio.dev/toolkits/blocknative/framework/mastra-ai)
- [LlamaIndex](https://composio.dev/toolkits/blocknative/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/blocknative/framework/crew-ai)

## TL;DR

Here's what you'll learn:
- Get and set up your OpenAI and Composio API keys
- Connect your Blocknative project to Composio
- Create a Tool Router MCP session for Blocknative
- Initialize an MCP client and retrieve Blocknative tools
- Build a LangChain agent that can interact with Blocknative
- Set up an interactive chat interface for testing

## What is LangChain?

LangChain is a framework for developing applications powered by language models. It provides tools and abstractions for building agents that can reason, use tools, and maintain conversation context.
Key features include:
- Agent Framework: Build agents that can use tools and make decisions
- MCP Integration: Connect to external services through Model Context Protocol adapters
- Memory Management: Maintain conversation history across interactions
- Multi-Provider Support: Works with OpenAI, Anthropic, and other LLM providers

## What is the Blocknative MCP server, and what's possible with it?

The Blocknative MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Blocknative account. It provides structured and secure access to real-time mempool data and transaction management features across public blockchains, so your agent can monitor transactions, analyze gas prices, configure filters, and manage blockchain event subscriptions on your behalf.
- Real-time mempool monitoring: Instruct your agent to subscribe to Ethereum transaction hashes or addresses and receive instant updates on their status and events.
- Gas price analysis and estimation: Have your agent fetch current gas price distributions, base fee predictions, and inclusion probability estimates to help optimize transaction fees.
- Customizable event filters: Let your agent configure advanced mempool filters and ABI decoding, so you can track only the events or transactions that matter to your workflow.
- Multichain event subscriptions: Enable your agent to subscribe or unsubscribe to transaction and account events across multiple supported blockchains using the Blocknative multichain SDK.
- Supported chain discovery: Ask your agent to list and discover which blockchains and gas oracles are available for monitoring and analytics.

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `BLOCKNATIVE_CONFIGURE_FILTERS` | Configure Mempool Filters | Tool to configure filters and ABI decoding for Ethereum mempool transactions. Use after establishing a Blocknative WebSocket connection to set up event filters and decoding. |
| `BLOCKNATIVE_GET_GAS_DISTRIBUTION` | Get Gas Price Distribution | Tool to retrieve the current mempool gas price distribution breakdown. Use when analyzing gas price trends or preparing fee strategies. |
| `BLOCKNATIVE_GET_GAS_ORACLES` | Get Gas Oracles | Tool to retrieve metadata on supported gas oracles per chain. Use when you need to dynamically discover all available on-chain gas estimation oracles across networks. |
| `BLOCKNATIVE_GET_GAS_PRICES` | Get Gas Prices | Tool to fetch gas price estimates for specific inclusion probabilities. Use when you need gas price ranges for the next block or next ~10 seconds. |
| `BLOCKNATIVE_GET_SUPPORTED_CHAINS` | Get Supported Chains | Tool to retrieve supported chains metadata. Use when discovering available networks for Blocknative gas services. |
| `BLOCKNATIVE_PREDICTION_API_BASEFEE_ESTIMATES` | Get Base Fee Estimates | Get real-time gas fee predictions for Ethereum mainnet's next 5 blocks. Returns base fee, blob base fee, and priority fee estimates at multiple confidence levels (99% and 50%). Essential for optimizing transaction costs and timing. Predictions include current block context (block number, time since last block) and estimated fees in gwei. |
| `BLOCKNATIVE_SUBSCRIBE_MULTICHAIN` | Subscribe Multichain | Generate WebSocket connection details to subscribe to real-time blockchain events (transactions or account activity) across multiple chains via Blocknative's Multichain API. Returns the WebSocket URL and subscription message payload needed to establish the connection and start receiving event notifications for a specific transaction hash or account address on any supported blockchain. |
| `BLOCKNATIVE_SUBSCRIBE_TRANSACTION_HASH` | Subscribe Transaction Hash | Tool to subscribe to transaction state change events of an Ethereum transaction hash. Use after establishing a Blocknative WebSocket connection to prepare the subscription message. |
| `BLOCKNATIVE_UNSUBSCRIBE_MULTICHAIN` | Unsubscribe Multichain | Tool to unsubscribe from events across multiple chains using the Multichain SDK. Use after stopping monitoring of an address or transaction to clean up resources, e.g., call: blocknative.unsubscribe({ id: '0x..', chainId: '0x1' }). |
| `BLOCKNATIVE_UNSUBSCRIBE_TRANSACTION_HASH` | Unsubscribe Transaction Hash | Tool to unsubscribe from transaction state change events for an Ethereum transaction hash. Use after establishing a Blocknative WebSocket connection to prepare the unsubscription message. |

## Supported Triggers

None listed.

## Creating MCP Server - Stand-alone vs Composio SDK

The Blocknative MCP server is an implementation of the Model Context Protocol that connects your AI agent to Blocknative. It provides structured and secure access so your agent can perform Blocknative operations on your behalf through a secure, permission-based interface.
With Composio's managed implementation, you don't have to create your own developer app. For production, if you're building an end product, we recommend using your own credentials. The managed server helps you prototype fast and go from 0-1 faster.

## Step-by-step Guide

### 1. Prerequisites

No description provided.

### 1. Getting API Keys for OpenAI and Composio

OpenAI API Key
- Go to the [OpenAI dashboard](https://platform.openai.com/settings/organization/api-keys) 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](https://dashboard.composio.dev?utm_source=toolkits&utm_medium=framework_docs).
- Navigate to your API settings and generate a new API key.
- Store this key securely as you'll need it for authentication.

### 2. Install dependencies

No description provided.
```python
pip install composio-langchain langchain-mcp-adapters langchain python-dotenv
```

```typescript
npm install @composio/langchain @langchain/core @langchain/openai @langchain/mcp-adapters dotenv
```

### 3. Set up environment variables

Create a .env file in your project root.
What's happening:
- COMPOSIO_API_KEY authenticates your requests to Composio's API
- COMPOSIO_USER_ID identifies the user for session management
- OPENAI_API_KEY enables access to OpenAI's language models
```bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_composio_user_id_here
OPENAI_API_KEY=your_openai_api_key_here
```

### 4. Import dependencies

No description provided.
```python
from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()
```

```typescript
import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

dotenv.config();
```

### 5. Initialize Composio client

What's happening:
- We're loading the COMPOSIO_API_KEY from environment variables and validating it exists
- Creating a Composio instance that will manage our connection to Blocknative tools
- Validating that COMPOSIO_USER_ID is also set before proceeding
```python
async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))

    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
```

```typescript
const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });
```

### 6. Create a Tool Router session

What's happening:
- We're creating a Tool Router session that gives your agent access to Blocknative 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
- This approach allows the agent to dynamically load and use Blocknative tools as needed
```python
# Create Tool Router session for Blocknative
session = composio.create(
    user_id=os.getenv("COMPOSIO_USER_ID"),
    toolkits=['blocknative']
)

url = session.mcp.url
```

```typescript
const session = await composio.create(
    userId as string,
    {
        toolkits: ['blocknative']
    }
);

const url = session.mcp.url;
```

### 7. Configure the agent with the MCP URL

No description provided.
```python
client = MultiServerMCPClient({
    "blocknative-agent": {
        "transport": "streamable_http",
        "url": session.mcp.url,
        "headers": {
            "x-api-key": os.getenv("COMPOSIO_API_KEY")
        }
    }
})

tools = await client.get_tools()

agent = create_agent("gpt-5", tools)
```

```typescript
const client = new MultiServerMCPClient({
    "blocknative-agent": {
        transport: "http",
        url: url,
        headers: {
            "x-api-key": process.env.COMPOSIO_API_KEY
        }
    }
});

const tools = await client.getTools();

const agent = createAgent({ model: "gpt-5", tools });
```

### 8. Set up interactive chat interface

No description provided.
```python
conversation_history = []

print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
print("Ask any Blocknative related question or task to the agent.\n")

while True:
    user_input = input("You: ").strip()

    if user_input.lower() in ['exit', 'quit', 'bye']:
        print("\nGoodbye!")
        break

    if not user_input:
        continue

    conversation_history.append({"role": "user", "content": user_input})
    print("\nAgent is thinking...\n")

    response = await agent.ainvoke({"messages": conversation_history})
    conversation_history = response['messages']
    final_response = response['messages'][-1].content
    print(f"Agent: {final_response}\n")
```

```typescript
let conversationHistory: any[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
console.log("Ask any Blocknative related question or task to the agent.\n");

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

rl.prompt();

rl.on('line', async (userInput: string) => {
    const trimmedInput = userInput.trim();

    if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
        console.log("\nGoodbye!");
        rl.close();
        process.exit(0);
    }

    if (!trimmedInput) {
        rl.prompt();
        return;
    }

    conversationHistory.push({ role: "user", content: trimmedInput });
    console.log("\nAgent is thinking...\n");

    const response = await agent.invoke({ messages: conversationHistory });
    conversationHistory = response.messages;

    const finalResponse = response.messages[response.messages.length - 1]?.content;
    console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\n👋 Session ended.');
        process.exit(0);
    });
```

### 9. Run the application

No description provided.
```python
if __name__ == "__main__":
    asyncio.run(main())
```

```typescript
main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});
```

## Complete Code

```python
from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()

async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))
    
    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
    
    session = composio.create(
        user_id=os.getenv("COMPOSIO_USER_ID"),
        toolkits=['blocknative']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "blocknative-agent": {
            "transport": "streamable_http",
            "url": url,
            "headers": {
                "x-api-key": os.getenv("COMPOSIO_API_KEY")
            }
        }
    })
    
    tools = await client.get_tools()
  
    agent = create_agent("gpt-5", tools)
    
    conversation_history = []
    
    print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
    print("Ask any Blocknative related question or task to the agent.\n")
    
    while True:
        user_input = input("You: ").strip()
        
        if user_input.lower() in ['exit', 'quit', 'bye']:
            print("\nGoodbye!")
            break
        
        if not user_input:
            continue
        
        conversation_history.append({"role": "user", "content": user_input})
        print("\nAgent is thinking...\n")
        
        response = await agent.ainvoke({"messages": conversation_history})
        conversation_history = response['messages']
        final_response = response['messages'][-1].content
        print(f"Agent: {final_response}\n")

if __name__ == "__main__":
    asyncio.run(main())
```

```typescript
import { Composio } from '@composio/core';
import { LangchainProvider } from '@composio/langchain';
import { MultiServerMCPClient } from "@langchain/mcp-adapters";  
import { createAgent } from "langchain";
import * as readline from 'readline';
import 'dotenv/config';

const composioApiKey = process.env.COMPOSIO_API_KEY;
const userId = process.env.COMPOSIO_USER_ID;

if (!composioApiKey) throw new Error('COMPOSIO_API_KEY is not set');
if (!userId) throw new Error('COMPOSIO_USER_ID is not set');

async function main() {
    const composio = new Composio({
        apiKey: composioApiKey as string,
        provider: new LangchainProvider()
    });

    const session = await composio.create(
        userId as string,
        {
            toolkits: ['blocknative']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "blocknative-agent": {
            transport: "http",
            url: url,
            headers: {
                "x-api-key": process.env.COMPOSIO_API_KEY
            }
        }
    });
    
    const tools = await client.getTools();
  
    const agent = createAgent({ model: "gpt-5", tools });
    
    let conversationHistory: any[] = [];
    
    console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
    console.log("Ask any Blocknative related question or task to the agent.\n");
    
    const rl = readline.createInterface({
        input: process.stdin,
        output: process.stdout,
        prompt: 'You: '
    });

    rl.prompt();

    rl.on('line', async (userInput: string) => {
        const trimmedInput = userInput.trim();
        
        if (['exit', 'quit', 'bye'].includes(trimmedInput.toLowerCase())) {
            console.log("\nGoodbye!");
            rl.close();
            process.exit(0);
        }
        
        if (!trimmedInput) {
            rl.prompt();
            return;
        }
        
        conversationHistory.push({ role: "user", content: trimmedInput });
        console.log("\nAgent is thinking...\n");
        
        const response = await agent.invoke({ messages: conversationHistory });
        conversationHistory = response.messages;
        
        const finalResponse = response.messages[response.messages.length - 1]?.content;
        console.log(`Agent: ${finalResponse}\n`);
        
        rl.prompt();
    });

    rl.on('close', () => {
        console.log('\nSession ended.');
        process.exit(0);
    });
}

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});
```

## Conclusion

You've successfully built a LangChain agent that can interact with Blocknative through Composio's Tool Router.
Key features of this implementation:
- Dynamic tool loading through Composio's Tool Router
- Conversation history maintenance for context-aware responses
- Async Python provides clean, efficient execution of agent workflows
You can extend this further by adding error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.

## How to build Blocknative MCP Agent with another framework

- [OpenAI Agents SDK](https://composio.dev/toolkits/blocknative/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/blocknative/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/blocknative/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/blocknative/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/blocknative/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/blocknative/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/blocknative/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/blocknative/framework/cli)
- [Google ADK](https://composio.dev/toolkits/blocknative/framework/google-adk)
- [Vercel AI SDK](https://composio.dev/toolkits/blocknative/framework/ai-sdk)
- [Mastra AI](https://composio.dev/toolkits/blocknative/framework/mastra-ai)
- [LlamaIndex](https://composio.dev/toolkits/blocknative/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/blocknative/framework/crew-ai)

## Related Toolkits

- [Supabase](https://composio.dev/toolkits/supabase) - Supabase is an open-source backend platform offering scalable Postgres databases, authentication, storage, and real-time APIs. It lets developers build modern apps without managing infrastructure.
- [Codeinterpreter](https://composio.dev/toolkits/codeinterpreter) - Codeinterpreter is a Python-based coding environment with built-in data analysis and visualization. It lets you instantly run scripts, plot results, and prototype solutions inside supported platforms.
- [GitHub](https://composio.dev/toolkits/github) - GitHub is a code hosting platform for version control and collaborative software development. It streamlines project management, code review, and team workflows in one place.
- [Ably](https://composio.dev/toolkits/ably) - Ably is a real-time messaging platform for live chat and data sync in modern apps. It offers global scale and rock-solid reliability for seamless, instant experiences.
- [Abuselpdb](https://composio.dev/toolkits/abuselpdb) - Abuselpdb is a central database for reporting and checking IPs linked to malicious online activity. Use it to quickly identify and report suspicious or abusive IP addresses.
- [Alchemy](https://composio.dev/toolkits/alchemy) - Alchemy is a blockchain development platform offering APIs and tools for Ethereum apps. It simplifies building and scaling Web3 projects with robust infrastructure.
- [Algolia](https://composio.dev/toolkits/algolia) - Algolia is a hosted search API that powers lightning-fast, relevant search experiences for web and mobile apps. It helps developers deliver instant, typo-tolerant, and scalable search without complex infrastructure.
- [Anchor browser](https://composio.dev/toolkits/anchor_browser) - Anchor browser is a developer platform for AI-powered web automation. It transforms complex browser actions into easy API endpoints for streamlined web interaction.
- [Apiflash](https://composio.dev/toolkits/apiflash) - Apiflash is a website screenshot API for programmatically capturing web pages. It delivers high-quality screenshots on demand for automation, monitoring, or reporting.
- [Apiverve](https://composio.dev/toolkits/apiverve) - Apiverve delivers a suite of powerful APIs that simplify integration for developers. It's designed for reliability and scalability so you can build faster, smarter applications without the integration headache.
- [Appcircle](https://composio.dev/toolkits/appcircle) - Appcircle is an enterprise-grade mobile CI/CD platform for building, testing, and publishing mobile apps. It streamlines mobile DevOps so teams ship faster and with more confidence.
- [Appdrag](https://composio.dev/toolkits/appdrag) - Appdrag is a cloud platform for building websites, APIs, and databases with drag-and-drop tools and code editing. It accelerates development and iteration by combining hosting, database management, and low-code features in one place.
- [Appveyor](https://composio.dev/toolkits/appveyor) - AppVeyor is a cloud-based continuous integration service for building, testing, and deploying applications. It helps developers automate and streamline their software delivery pipelines.
- [Backendless](https://composio.dev/toolkits/backendless) - Backendless is a backend-as-a-service platform for mobile and web apps, offering database, file storage, user authentication, and APIs. It helps developers ship scalable applications faster without managing server infrastructure.
- [Baserow](https://composio.dev/toolkits/baserow) - Baserow is an open-source no-code database platform for building collaborative data apps. It makes it easy for teams to organize data and automate workflows without writing code.
- [Bench](https://composio.dev/toolkits/bench) - Bench is a benchmarking tool for automated performance measurement and analysis. It helps you quickly evaluate, compare, and track your systems or workflows.
- [Better stack](https://composio.dev/toolkits/better_stack) - Better Stack is a monitoring, logging, and incident management solution for apps and services. It helps teams ensure application reliability and performance with real-time insights.
- [Bitbucket](https://composio.dev/toolkits/bitbucket) - Bitbucket is a Git-based code hosting and collaboration platform for teams. It enables secure repository management and streamlined code reviews.
- [Blazemeter](https://composio.dev/toolkits/blazemeter) - Blazemeter is a continuous testing platform for web and mobile app performance. It empowers teams to automate and analyze large-scale tests with ease.
- [Bolt iot](https://composio.dev/toolkits/bolt_iot) - Bolt IoT is a platform for building and managing IoT projects with cloud-based device control and monitoring. It makes connecting sensors and actuators to the internet seamless for automation and data insights.

## Frequently Asked Questions

### What are the differences in Tool Router MCP and Blocknative MCP?

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

### Can I use Tool Router MCP with LangChain?

Yes, you can. LangChain 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 Blocknative tools.

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

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

---
[See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)