How to integrate Affinity MCP with LangChain

This guide walks you through connecting Affinity to LangChain using the Composio tool router. By the end, you'll have a working Affinity agent that can list all companies added this week, show all opportunities in active pipeline, get recent contacts linked to acme corp through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Affinity account through Composio's Affinity MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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Affinity

Api Key

Affinity is a relationship intelligence CRM that helps private capital investors find, manage, and close more deals. It streamlines deal flow and surfaces key connections to help you win opportunities.

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Introduction

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

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

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

The Affinity MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Affinity account. It provides structured and secure access to your deal, company, and contact data, so your agent can analyze lists, fetch opportunity details, extract company insights, and organize people or organizations on your behalf.

Company data extraction and analysis: Let your agent retrieve detailed company profiles, summarize list entries, and pull custom field data for deeper insights and reporting.
Opportunity pipeline management: Automatically fetch and review all ongoing opportunities, track changes, and surface high-priority deals for follow-up.
List and view organization: Ask your agent to access entries across lists or saved views, aggregating metadata and field values for efficient CRM workflows.
Contact and relationship intelligence: Effortlessly browse, analyze, and summarize person records, including their list memberships, activity, and custom fields.
Automated CRM reporting: Generate summaries, export data, and monitor changes across companies, people, and opportunities to keep your pipeline up-to-date and actionable.

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

Step by step10 STEPS

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

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

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

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 Affinity functionality through MCP

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 Affinity tools
Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

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

const url = session.mcp.url;

What's happening:

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

Configure the agent with the MCP URL

const client = new MultiServerMCPClient({
    "affinity-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 Affinity MCP server via HTTP
The client is configured with a name and the URL from our Tool Router session
getTools() retrieves all available Affinity tools that the agent can use
We're creating a LangChain agent using the GPT-5 model

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 Affinity 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

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 Affinity 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: ['affinity']
        }
    );

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

Get a company s list entries

Summarize company data across all lists, including list-specific fields and metadata like creation date and author.

Get a company s lists

Returns metadata for all the Lists on which the given Company appears.

Get all companies

Affinity API allows paginated access to company info and custom fields.

Get all list entries on a list

Access and export essential data and metadata for Companies, Persons, or Opportunities from a List, specifying data via `fieldIds` or `fieldTypes`.

Get all list entries on a saved view

Use the endpoint to access rows in a Saved View with specific filters and selected fields from a web app.

Get all opportunities

Pagination through Opportunities in Affinity yields basic info but excludes field data.

Get all persons

The Affinity API offers paginated access to Person data using `fieldIds` or `fieldTypes`.

Get a person s list entries

Summary: Browse rows for a Person in all Lists, showing field data and entry metadata like creation time and author.

Get a person s lists

Returns metadata for all the Lists on which the given Person appears.

Get a single company

Retrieve basic company info and specific field data by using `fieldIds` or `fieldTypes` parameters.

Get a single opportunity

Get basic details about an Opportunity without field data via provided endpoints.

Get a single person

Use GET `/v2/persons/fields` with `fieldIds` or `fieldTypes` for detailed data; basic info by default.

Get current user

Returns metadata about the current user.

Get metadata on all lists

Returns metadata on Lists.

Get metadata on a single list

Returns metadata on a single List.

Get metadata on a single list s fields

Returns metadata on the Fields available on a single List.

Get metadata on a single saved view

Returns metadata on a single Saved View.

Get metadata on company fields

Returns metadata on non-list-specific Company Fields.

Get metadata on person fields

Returns metadata on non-list-specific Person Fields.

Get metadata on saved views

Returns metadata on the Saved Views on a List.

FRAMEWORKS

How to build Affinity MCP Agent with another framework

OpenAI Agents SDK

Use Affinity MCP with OpenAI Agents SDK

Claude Agent SDK

Use Affinity MCP with Claude Agent SDK

Claude Code

Use Affinity MCP with Claude Code

Claude Cowork

Use Affinity MCP with Claude Cowork

Codex

Use Affinity MCP with Codex

OpenClaw

Use Affinity MCP with OpenClaw

Hermes

Use Affinity MCP with Hermes

CLI

Use Affinity MCP with CLI

Google ADK

Use Affinity MCP with Google ADK

Vercel AI SDK

Use Affinity MCP with Vercel AI SDK

Mastra AI

Use Affinity MCP with Mastra AI

LlamaIndex

Use Affinity MCP with LlamaIndex

CrewAI

Use Affinity MCP with CrewAI

MORE TOOLKITS

Explore Other Toolkits

Toolkit marketplace

Hubspot

Oauth2Api Key

HubSpot is an all-in-one marketing, sales, and customer service platform. It lets teams nurture leads, automate outreach, and track every customer interaction in one place.

Pipedrive

Oauth2Api Key

Pipedrive is a sales management platform offering pipeline visualization, lead tracking, and workflow automation. It helps sales teams keep deals moving forward efficiently and never miss a follow-up.

Salesforce

Oauth2S2s Oauth2

Salesforce is a leading CRM platform that helps businesses manage sales, service, and marketing. It centralizes customer data, enabling teams to drive growth and build strong relationships.

Apollo

Api Key

Apollo is a CRM and lead generation platform that helps businesses discover contacts and manage sales pipelines. Use it to streamline customer outreach and track your deals from one place.

FAQ

Frequently asked questions

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

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

Start with Affinity.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Affinity tool your agent needs.Free to start.

Start building

Customer stories

Teams ship real agents on Composio

GET STARTED FOR FREE BOOK A DEMO

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

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

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

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

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

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

Co-Founder, Ingram Technologies

How to integrate Affinity MCP with LangChain

Connect Affinity without auth hassles

Introduction

Also integrate Affinity with

TL;DR

What is LangChain?

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

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

Supported Tools

How to build Affinity 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

Hubspot

Pipedrive

Salesforce

Apollo

Frequently asked questions

What are the differences in Tool Router MCP and Affinity MCP?+

Can I use Tool Router MCP with LangChain?+

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

How safe is my data with Composio Tool Router?+

Start with Affinity.It takes 30 seconds.

Teams ship real agents on Composio