How to integrate Human Approval - HITL Platform MCP with LangChain

This guide walks you through connecting Human Approval - HITL Platform to LangChain using the Composio tool router. By the end, you'll have a working Human Approval - HITL Platform agent that can request human approval, review approval requests, cancel requests, manage loops, and list loop members through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Human Approval - HITL Platform account through Composio's Human Approval - HITL Platform MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Api Key

Human Approval - HITL Platform is a HITL.sh service for adding human approval and review workflows to AI agents. Use it to pause risky automations, collect structured decisions, and resume safely.

10 Tools

Introduction

This guide walks you through connecting Human Approval - HITL Platform to LangChain using the Composio tool router. By the end, you'll have a working Human Approval - HITL Platform agent that can request human approval, review approval requests, cancel requests, manage loops, and list loop members through natural language commands.

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

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

Also integrate Human Approval - HITL Platform 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 Human Approval - HITL Platform project to Composio
  • Create a Tool Router MCP session for Human Approval - HITL Platform
  • Initialize an MCP client and retrieve Human Approval - HITL Platform tools
  • Build a LangChain agent that can interact with Human Approval - HITL Platform
  • 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 Human Approval - HITL Platform MCP server, and what's possible with it?

The Human Approval - HITL Platform MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Human Approval - HITL Platform account. It provides structured and secure access to your human approval loops and review requests, so your agent can organize reviewers, request decisions, track responses, cancel pending reviews, and manage approval loops on your behalf.

  • Approval loop management: Have your agent create, rename, describe, list, or permanently delete approval loops for different teams and workflows.
  • Reviewer readiness checks: Let the agent list active and pending reviewers in a loop before sending work for human approval.
  • Human approval requests: Direct your agent to create and broadcast structured approval requests to the active reviewers in a chosen loop.
  • Decision tracking and cancellation: Instruct your agent to check an approval request's status and human response, list previous requests, or cancel a pending request.
  • Account and allowance checks: Have your agent verify the connected account's status, permissions, and remaining request allowance before asking for approval.

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 Human Approval - HITL Platform 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 Human Approval - HITL Platform 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: ['hitl']
    }
);

const url = session.mcp.url;
What's happening:
  • We're creating a Tool Router session that gives your agent access to Human Approval - HITL Platform 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 Human Approval - HITL Platform tools as needed
8

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "hitl-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 Human Approval - HITL Platform MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • getTools() retrieves all available Human Approval - HITL Platform 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 Human Approval - HITL Platform 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 Human Approval - HITL Platform 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: ['hitl']
        }
    );

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "hitl-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 Human Approval - HITL Platform 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 Human Approval - HITL Platform 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 Human Approval - HITL Platform action and event your agent gets out of the box.

Cancel Approval Request

Irreversibly cancel a pending approval request so reviewers can no longer complete it.

Create Approval Request

Create and broadcast one human approval request to active members of an owned loop, consuming one provider request allowance.

Create Loop

Create an approval loop and return its loop ID and human invitation links; the connected account is added as an active member.

Delete Loop

Permanently delete an owned loop and all of its memberships, approval requests, responses, feedback, and analytics.

Get Account Status

Return the connected HITL account identity, status, permissions, and provider-reported request allowance before creating an approval request.

Get Approval Request

Get the current status, configuration, and human response for one approval request; use for deliberate polling after creation.

List Approval Requests

Return approval requests created by the connected API key, optionally restricted to one loop; pagination controls are omitted because the live API currently ignores them.

List Loop Members

Return a loop's active and pending human reviewers so an agent can verify readiness before broadcasting an approval request.

List Loops

Return all approval loops owned by the connected account, including embedded members and membership counts.

Update Loop

Update one or more display fields of an owned approval loop without changing its members or requests.

FRAMEWORKS

How to build Human Approval - HITL Platform MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Human Approval - HITL Platform MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Human Approval - HITL Platform MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Human Approval - HITL Platform MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Human Approval - HITL Platform MCP with Claude Cowork

Codex logo

Codex

Use Human Approval - HITL Platform MCP with Codex

OpenClaw logo

OpenClaw

Use Human Approval - HITL Platform MCP with OpenClaw

Hermes logo

Hermes

Use Human Approval - HITL Platform MCP with Hermes

CLI logo

CLI

Use Human Approval - HITL Platform MCP with CLI

Google ADK logo

Google ADK

Use Human Approval - HITL Platform MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Human Approval - HITL Platform MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Human Approval - HITL Platform MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Human Approval - HITL Platform MCP with LlamaIndex

CrewAI logo

CrewAI

Use Human Approval - HITL Platform MCP with CrewAI

FAQ

Frequently asked questions

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

Yes, absolutely. You can configure which Human Approval - HITL Platform 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 Human Approval - HITL Platform data and credentials are handled as safely as possible.

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