How to integrate Nextdns MCP with LangChain

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.

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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 SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKVercel AI SDKMastra AILlamaIndexCrewAI

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.

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 step10 STEPS
1

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
2

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.
3

Install dependencies

npm install @composio/langchain @langchain/core @langchain/openai @langchain/mcp-adapters 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/core is the core agent framework
  • dotenv/config loads environment variables
4

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
5

Import dependencies

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();
What's happening:
  • We're importing LangChain's MCP adapter and Composio SDK
  • The dotenv/config import loads environment variables from your .env file
  • This setup prepares the foundation for connecting LangChain with Nextdns functionality through MCP
6

Initialize Composio client

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()
    });
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
7

Create a Tool Router session

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

const 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
8

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "nextdns-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 });
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
  • getTools() retrieves all available Nextdns tools that the agent can use
  • We're creating a LangChain agent using the GPT-5 model
9

Set up interactive chat interface

let conversationHistory: any[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
console.log("Ask any Nextdns 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);
    });
What's happening:
  • We initialize an empty conversationHistory list to maintain context across interactions
  • A readline interface is used to continuously accept 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 invoke() method with the full conversation history
  • Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully
10

Run the application

main().catch((err) => {
    console.error('Fatal error:', err);
    process.exit(1);
});
What's happening:
  • We call the main() function to start the application

Complete Code

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

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: ['nextdns']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "nextdns-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 Nextdns 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 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.
TOOLS

Supported Tools

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

Add Allowlist Entry

Tool to add a domain to the allowlist of a NextDNS profile.

Add Blocked TLD

Tool to add a top-level domain to the security blocklist for a NextDNS profile.

Add Denylist Domain

Tool to add a domain to the denylist of a NextDNS profile.

Add Parental Control Category

Tool to add a content category to the parental control categories list.

Add Parental Control Service

Tool to add a service to the parental control services list of a NextDNS profile.

Add Privacy Blocklist

Tool to add a blocklist to the privacy blocklists for a NextDNS profile.

Add Privacy Native Tracker

Tool to add a native tracking service to the blocked list for a NextDNS profile.

Add DNS Rewrite Rule

Tool to add a DNS rewrite rule to a NextDNS profile.

Clear Logs

Tool to clear DNS logs for a NextDNS profile.

Create Profile

This tool allows users to create a new NextDNS profile.

Delete Allowlist Entry

Tool to remove a domain from a NextDNS profile's allowlist.

Delete NextDNS Configuration

Tool to delete a NextDNS configuration profile.

Delete Parental Control Category

Tool to remove a category from parental control blocked categories.

Delete Parental Control Service

Tool to remove a service from parental control blocked services.

Delete Privacy Blocklist

Tool to remove a blocklist from the privacy blocklists for a NextDNS profile.

Delete Privacy Native Tracker

Tool to remove a native tracking entry from a NextDNS profile's privacy settings.

Delete DNS Rewrite Rule

Tool to delete a DNS rewrite rule from a NextDNS profile.

Download Logs

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

Get Allowlist

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

Get Analytics Destinations

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

Get Analytics Devices

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

Get Analytics DNSSEC

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

Get Analytics Domains

Tool to retrieve analytics data for domains within a specific profile.

Get Analytics Encryption

Tool to retrieve encryption analytics for a profile showing encrypted vs unencrypted query counts.

Get Analytics IPs

Tool to retrieve analytics aggregated by client IP addresses.

Get Analytics IP Versions

Tool to retrieve analytics grouped by IP version within a specific profile.

Get Analytics Protocols

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

Get Analytics Query Types

Tool to retrieve DNS query counts broken down by query type.

Get Analytics Blocking Reasons

Tool to retrieve blocking reasons analytics showing blocklists, native tracking protection, and other reasons for blocked queries.

Get Analytics Status

Tool to retrieve analytics status for a specific profile.

Get Logs

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

Get Parental Control Settings

Tool to get parental control settings for a profile.

Get Parental Control Categories

Tool to get the list of blocked/allowed content categories for parental control.

Get Parental Control Services

Tool to get the list of blocked/allowed services for parental control.

Get Performance Settings

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

Get Privacy Settings

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

Get Profile Details

Retrieves the details of a specific NextDNS profile.

Get DNS Rewrites

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

Get Security TLDs

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

Get Profile Settings

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

Get Block Page Settings

Tool to retrieve the block page settings for a NextDNS profile.

Get Logging Settings

Tool to retrieve the logging settings for a NextDNS profile.

List Denylist Domains

Tool to list domains in the denylist for a profile.

List Profiles

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

List Security Settings

Tool to list current security options for a NextDNS configuration.

Log Client IPs

Tool to enable or disable logging of client IPs for a NextDNS configuration.

Toggle Domain Logging

Tool to enable or disable logging of domains for a NextDNS profile.

Remove Blocked TLD

Tool to remove a top-level domain from the security blocklist for a NextDNS profile.

Remove Denylist Domain

Removes a domain from a NextDNS profile's denylist (blocklist).

Rename Configuration

Tool to rename a NextDNS configuration (profile).

Replace Allowlist

Tool to replace the entire allowlist for a NextDNS profile.

Replace Denylist

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

Replace Parental Control Categories

Tool to replace the entire list of blocked/allowed content categories for parental control.

Replace Parental Control Services

Tool to replace the entire list of blocked/allowed services for parental control.

Replace Privacy Blocklists

Tool to replace the entire list of privacy blocklists for a NextDNS profile.

Replace Privacy Native Tracking Services

Tool to replace the entire list of blocked native tracking services for a NextDNS profile.

Replace Security TLDs

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

Update Allowlist Entry

Tool to update a specific allowlist entry in a NextDNS profile.

Update Denylist Entry

Updates a specific denylist entry in a NextDNS profile, typically to toggle its active status.

Update linked IP

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

Update Parental Control Settings

Tool to update parental control settings for a NextDNS profile.

Update Parental Control Category

Tool to update a specific category entry in parental control settings.

Update Parental Control Service

Tool to update a specific service entry in parental control settings.

Update Performance Settings

Tool to update performance settings of a NextDNS profile.

Update Privacy Settings

Tool to update privacy settings for a profile.

Update Security Settings

Tool to update security settings for a profile.

Update Settings

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

Update Block Page Settings

Tool to update block page settings for a NextDNS profile.

FRAMEWORKS

How to build Nextdns MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Nextdns MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Nextdns MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Nextdns MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Nextdns MCP with Claude Cowork

Codex logo

Codex

Use Nextdns MCP with Codex

OpenClaw logo

OpenClaw

Use Nextdns MCP with OpenClaw

Hermes logo

Hermes

Use Nextdns MCP with Hermes

CLI logo

CLI

Use Nextdns MCP with CLI

Google ADK logo

Google ADK

Use Nextdns MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Nextdns MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Nextdns MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Nextdns MCP with LlamaIndex

CrewAI logo

CrewAI

Use Nextdns MCP with CrewAI

FAQ

Frequently asked questions

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.

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.

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.

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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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
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
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
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
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
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
Jerome Leclanche
Co-Founder, Ingram Technologies