How to integrate Splitwise MCP with LangChain

This guide walks you through connecting Splitwise to LangChain using the Composio tool router. By the end, you'll have a working Splitwise agent that can add a new friend using their email, create a dinner expense split equally, list all groups i'm part of through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Splitwise account through Composio's Splitwise MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Splitwise helps you split bills and expenses with friends and family. It makes it easy to track shared costs and settle up, so everyone stays on the same page.

27 Tools

Introduction

This guide walks you through connecting Splitwise to LangChain using the Composio tool router. By the end, you'll have a working Splitwise agent that can add a new friend using their email, create a dinner expense split equally, list all groups i'm part of through natural language commands.

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

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

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

The Splitwise MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Splitwise account. It provides structured and secure access to your expenses and group data, so your agent can perform actions like creating expenses, adding friends, retrieving categories, and managing your account on your behalf.

  • Expense tracking and creation: Quickly have your agent record new expenses, split bills, or log payments—either between you and friends or within groups.
  • Friend and contact management: Easily add new friends with their email and name, or remove existing friends to keep your network current.
  • Group info and collaboration: Retrieve details about any group you belong to, making it simple to manage shared costs and stay organized with your housemates, travel buddies, or teams.
  • Expense category and currency lookup: Ask the agent to fetch available expense categories or supported currencies, helping you record transactions accurately and consistently.
  • Account and profile insights: Let your agent pull your current user details so you can quickly review account information or verify profile data as needed.

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 Splitwise 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 Splitwise 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: ['splitwise']
    }
);

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

Configure the agent with the MCP URL

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

    const url = session.mcp.url;
    
    const client = new MultiServerMCPClient({
        "splitwise-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 Splitwise 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 Splitwise 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 Splitwise action and event your agent gets out of the box.

Add Friend

Tool to add a new friend to Splitwise.

Add User to Group

Tool to add a user to a group.

Create Comment

Tool to create a comment on a specific expense.

Create Expense

Tool to create a new Splitwise expense.

Create Friends

Tool to add multiple friends at once to Splitwise.

Create Group

Tool to create a new group in Splitwise.

Delete Comment

Tool to delete a comment by its ID.

Delete Expense

Tool to delete an existing expense by its ID.

Delete Friend

Tool to delete an existing friend by ID.

Delete Group

Tool to delete a group and all associated records by its ID.

Get Categories

Tool to retrieve expense categories.

Get Comments

Tool to retrieve all comments associated with a specific expense.

Get Currencies

Tool to retrieve a list of supported currencies.

Get Current User

Tool to retrieve information about the current authenticated user.

Get Expense

Tool to retrieve detailed information about a specific expense by ID.

Get Expenses

Tool to list the current user's expenses from Splitwise account.

Get Friend Details

Tool to retrieve detailed information about a specific friend.

Get Friends

Tool to list current user's friends on Splitwise.

Get Group Details

Tool to retrieve detailed information about a specific group.

Get Groups

Retrieves all groups the authenticated user belongs to, including group details, members, balances, and debt information.

Get Notifications

Tool to retrieve recent activity notifications from the user's Splitwise account.

Get User Information

Retrieves basic profile information about any Splitwise user by their ID.

Remove User from Group

Tool to remove a user from a group.

Restore Deleted Expense

Tool to restore a previously deleted expense and its associated records.

Restore Deleted Group

Tool to restore a previously deleted group and all its associated records.

Update Expense

Tool to update an existing Splitwise expense.

Update User

Tool to update user account details including name, email, password, and preferences.

FRAMEWORKS

How to build Splitwise MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Splitwise MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Splitwise MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Splitwise MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Splitwise MCP with Claude Cowork

Codex logo

Codex

Use Splitwise MCP with Codex

OpenClaw logo

OpenClaw

Use Splitwise MCP with OpenClaw

Hermes logo

Hermes

Use Splitwise MCP with Hermes

CLI logo

CLI

Use Splitwise MCP with CLI

Google ADK logo

Google ADK

Use Splitwise MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Splitwise MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Splitwise MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Splitwise MCP with LlamaIndex

CrewAI logo

CrewAI

Use Splitwise MCP with CrewAI

FAQ

Frequently asked questions

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

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

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