Nextdns with LangChain

How to integrate Nextdns MCP with LangChain

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Introduction Also integrate Nextdns with TL;DR What is LangChain What is the Nextdns MCP server Supported Tools & Triggers Creating MCP Server - Stand-alone vs Composio SDK Step-by-step Guide Complete Code Conclusion How to build Nextdns MCP Agent with another framework Explore Other Toolkits FAQ

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Introduction

This guide walks you through connecting Nextdns to LangChain using the Composio tool router. By the end, you'll have a working Nextdns agent that can block access to adult websites for a profile, download dns logs from last week, show top domains queried by your devices through natural language commands.

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

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

Also integrate Nextdns with

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

TL;DR

Here's what you'll learn:

Get and set up your OpenAI and Composio API keys
Connect your Nextdns project to Composio
Create a Tool Router MCP session for Nextdns
Initialize an MCP client and retrieve Nextdns tools
Build a LangChain agent that can interact with Nextdns
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 Nextdns MCP server, and what's possible with it?

The Nextdns MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Nextdns account. It provides structured and secure access to your DNS security and privacy controls, so your agent can perform actions like blocking domains, managing profiles, analyzing DNS analytics, and clearing logs on your behalf.

Dynamic domain and TLD blocking: Instantly add domains or top-level domains to your denylist or security blocklist, helping you stay ahead of new threats.
Profile management and configuration: Create, update, or delete NextDNS configuration profiles to tailor DNS filtering and security settings for different users or devices.
Comprehensive DNS analytics: Retrieve detailed analytics by device, domain, or client IP to monitor DNS activity, spot anomalies, and optimize security policies.
Log management and export: Download DNS query logs for audit or troubleshooting, or clear logs entirely to maintain your privacy.
Control over block page settings: Enable or disable the block page for any configuration, giving you flexibility over how blocks are displayed to users.

Supported Tools & Triggers

Tools

Add Allowlist EntryTool to add a domain to the allowlist of a NextDNS profile.

Add Blocked TLDTool to add a top-level domain to the security blocklist for a NextDNS profile.

Add Denylist DomainTool to add a domain to the denylist of a NextDNS profile.

Add Parental Control CategoryTool to add a content category to the parental control categories list.

Add Parental Control ServiceTool to add a service to the parental control services list of a NextDNS profile.

Add Privacy BlocklistTool to add a blocklist to the privacy blocklists for a NextDNS profile.

Add Privacy Native TrackerTool to add a native tracking service to the blocked list for a NextDNS profile.

Add DNS Rewrite RuleTool to add a DNS rewrite rule to a NextDNS profile.

Clear LogsTool to clear DNS logs for a NextDNS profile.

Create ProfileThis tool allows users to create a new NextDNS profile.

Delete Allowlist EntryTool to remove a domain from a NextDNS profile's allowlist.

Delete NextDNS ConfigurationTool to delete a NextDNS configuration profile.

Delete Parental Control CategoryTool to remove a category from parental control blocked categories.

Delete Parental Control ServiceTool to remove a service from parental control blocked services.

Delete Privacy BlocklistTool to remove a blocklist from the privacy blocklists for a NextDNS profile.

Delete Privacy Native TrackerTool to remove a native tracking entry from a NextDNS profile's privacy settings.

Delete DNS Rewrite RuleTool to delete a DNS rewrite rule from a NextDNS profile.

Download LogsRetrieves the download URL for exported DNS query logs from a NextDNS profile.

Get AllowlistTool to retrieve the list of allowed domains for a NextDNS profile.

Get Analytics DestinationsTool to retrieve destination analytics for a profile showing query destinations by country or GAFAM company.

Get Analytics DevicesTool to retrieve device analytics for a profile showing identified devices with names, models, and query counts.

Get Analytics DNSSECTool to retrieve DNSSEC validation analytics for a profile showing validated vs non-validated query counts.

Get Analytics DomainsTool to retrieve analytics data for domains within a specific profile.

Get Analytics EncryptionTool to retrieve encryption analytics for a profile showing encrypted vs unencrypted query counts.

Get Analytics IPsTool to retrieve analytics aggregated by client IP addresses.

Get Analytics IP VersionsTool to retrieve analytics grouped by IP version within a specific profile.

Get Analytics ProtocolsTool to retrieve protocol analytics for a specific profile showing DNS protocol distribution (DNS-over-HTTPS, DNS-over-TLS, UDP).

Get Analytics Query TypesTool to retrieve DNS query counts broken down by query type.

Get Analytics Blocking ReasonsTool to retrieve blocking reasons analytics showing blocklists, native tracking protection, and other reasons for blocked queries.

Get Analytics StatusTool to retrieve analytics status for a specific profile.

Get LogsTool to retrieve logs for a specific NextDNS profile with optional filters.

Get Parental Control SettingsTool to get parental control settings for a profile.

Get Parental Control CategoriesTool to get the list of blocked/allowed content categories for parental control.

Get Parental Control ServicesTool to get the list of blocked/allowed services for parental control.

Get Performance SettingsTool to get performance settings for a profile including ECS, cache boost, and CNAME flattening configuration.

Get Privacy SettingsTool to get privacy settings for a profile including blocklists, native tracking settings, disguised trackers, and affiliate settings.

Get Profile DetailsRetrieves the details of a specific NextDNS profile.

Get DNS RewritesTool to retrieve the list of DNS rewrites for a NextDNS profile.

Get Security TLDsTool to get the list of blocked TLDs (top-level domains) for a profile's security settings.

Get Profile SettingsTool to get all settings for a NextDNS profile including logs, block page, performance, and web3 settings.

Get Block Page SettingsTool to retrieve the block page settings for a NextDNS profile.

Get Logging SettingsTool to retrieve the logging settings for a NextDNS profile.

List Denylist DomainsTool to list domains in the denylist for a profile.

List ProfilesList all NextDNS profiles for the authenticated user, returning profile IDs and configurations.

List Security SettingsTool to list current security options for a NextDNS configuration.

Log Client IPsTool to enable or disable logging of client IPs for a NextDNS configuration.

Toggle Domain LoggingTool to enable or disable logging of domains for a NextDNS profile.

Remove Blocked TLDTool to remove a top-level domain from the security blocklist for a NextDNS profile.

Remove Denylist DomainRemoves a domain from a NextDNS profile's denylist (blocklist).

Rename ConfigurationTool to rename a NextDNS configuration (profile).

Replace AllowlistTool to replace the entire allowlist for a NextDNS profile.

Replace DenylistTool to replace the entire denylist (blocked domains) for a NextDNS profile.

Replace Parental Control CategoriesTool to replace the entire list of blocked/allowed content categories for parental control.

Replace Parental Control ServicesTool to replace the entire list of blocked/allowed services for parental control.

Replace Privacy BlocklistsTool to replace the entire list of privacy blocklists for a NextDNS profile.

Replace Privacy Native Tracking ServicesTool to replace the entire list of blocked native tracking services for a NextDNS profile.

Replace Security TLDsTool to replace the entire list of blocked TLDs (top-level domains) for a NextDNS profile's security settings.

Update Allowlist EntryTool to update a specific allowlist entry in a NextDNS profile.

Update Denylist EntryUpdates a specific denylist entry in a NextDNS profile, typically to toggle its active status.

Update linked IPUpdates the linked IP address for a NextDNS profile to the current caller's public IP.

Update Parental Control SettingsTool to update parental control settings for a NextDNS profile.

Update Parental Control CategoryTool to update a specific category entry in parental control settings.

Update Parental Control ServiceTool to update a specific service entry in parental control settings.

Update Performance SettingsTool to update performance settings of a NextDNS profile.

Update Privacy SettingsTool to update privacy settings for a profile.

Update Security SettingsTool to update security settings for a profile.

Update SettingsTool to update settings for a NextDNS profile including logs, block page, performance, and web3 settings.

Update Block Page SettingsTool to update block page settings for a NextDNS profile.

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

Prerequisites

Before starting this tutorial, make sure you have:

Python 3.10 or higher installed on your system
A Composio account with an API key
An OpenAI 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

pip install composio-langchain langchain-mcp-adapters langchain python-dotenv

Install the required packages for LangChain with MCP support.

What's happening:

composio-langchain provides Composio integration for LangChain
langchain-mcp-adapters enables MCP client connections
langchain is the core agent framework
python-dotenv loads environment variables

Set up environment variables

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

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

Import dependencies

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()

What's happening:

We're importing LangChain's MCP adapter and Composio SDK
The dotenv import loads environment variables from your .env file
This setup prepares the foundation for connecting LangChain with Nextdns functionality through MCP

Initialize Composio client

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")

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 Nextdns tools
Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

# Create Tool Router session for Nextdns
session = composio.create(
    user_id=os.getenv("COMPOSIO_USER_ID"),
    toolkits=['nextdns']
)

url = session.mcp.url

What's happening:

We're creating a Tool Router session that gives your agent access to Nextdns 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 Nextdns tools as needed

Configure the agent with the MCP URL

client = MultiServerMCPClient({
    "nextdns-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)

What's happening:

We're creating a MultiServerMCPClient that connects to our Nextdns MCP server via HTTP
The client is configured with a name and the URL from our Tool Router session
get_tools() retrieves all available Nextdns tools that the agent can use
We're creating a LangChain agent using the GPT-5 model

Set up interactive chat interface

conversation_history = []

print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
print("Ask any Nextdns 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")

What's happening:

We initialize an empty conversation_history list to maintain context across interactions
A while loop continuously accepts user input from the command line
When a user types a message, it's added to the conversation history and sent to the agent
The agent processes the request using the ainvoke() method with the full conversation history
Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully

Run the application

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

What's happening:

We call the main() function using asyncio.run() to start the application

Complete Code

Here's the complete code to get you started with Nextdns and LangChain:

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=['nextdns']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "nextdns-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 Nextdns 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())

Conclusion

You've successfully built a LangChain agent that can interact with Nextdns 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.

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FAQ

What are the differences in Tool Router MCP and Nextdns MCP?

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

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

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

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Harsha GaddipatiCo-founder, Slashy

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

Abhi AryaCo-founder, Opennote

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 has immensely helped in keeping new users on the platform.

Nirman DaveCEO, Zams

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

Ryan YuFounder, Extra Thursday

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

Tomisin JenrolaFounder & CEO, SwarmZero

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

Jerome LeclancheCo-Founder, Ingram Technologies

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.

Harsha GaddipatiCo-founder, Slashy

Abhi AryaCo-founder, Opennote

Nirman DaveCEO, Zams

Ryan YuFounder, Extra Thursday

Tomisin JenrolaFounder & CEO, SwarmZero

Jerome LeclancheCo-Founder, Ingram Technologies

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.

Harsha GaddipatiCo-founder, Slashy

Abhi AryaCo-founder, Opennote

Nirman DaveCEO, Zams

Ryan YuFounder, Extra Thursday

Tomisin JenrolaFounder & CEO, SwarmZero

Jerome LeclancheCo-Founder, Ingram Technologies

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.

How to integrate Nextdns MCP with LangChain

Table of Contents

Connect Nextdns without Auth hassles

Introduction

Also integrate Nextdns with

TL;DR

What is LangChain?

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

Supported Tools & Triggers

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 OpenAI and Composio

Install dependencies

Set up environment variables

Import dependencies

Initialize Composio client

Create a Tool Router session

Configure the agent with the MCP URL

Set up interactive chat interface

Run the application

Complete Code

Conclusion

How to build Nextdns MCP Agent with another framework

OpenAI Agents SDK

Claude Agent SDK

Claude Code

Claude Cowork

Codex

OpenClaw

Hermes

CLI

Google ADK

Vercel AI SDK

Mastra AI

LlamaIndex

CrewAI

Explore Other Toolkits

Excel

21risk

Abstract

FAQ

What are the differences in Tool Router MCP and Nextdns MCP?

Can I use Tool Router MCP with LangChain?

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

How safe is my data with Composio Tool Router?

Used by agents from

Never worry about agent reliability