How to integrate Census bureau MCP with LangChain

This guide walks you through connecting Census bureau to LangChain using the Composio tool router. By the end, you'll have a working Census bureau agent that can get latest population estimate for los angeles county, list top industries in texas by employment, fetch 5-year acs median income for chicago through natural language commands. This guide will help you understand how to give your LangChain agent real control over a Census bureau account through Composio's Census bureau 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

Census bureau is the U.S. Census Bureau’s official data API, offering access to nationwide demographic, economic, and geographic statistics. It lets you power your applications and automations with up-to-date, authoritative U.S. data.

81 Tools

Introduction

This guide walks you through connecting Census bureau to LangChain using the Composio tool router. By the end, you'll have a working Census bureau agent that can get latest population estimate for los angeles county, list top industries in texas by employment, fetch 5-year acs median income for chicago through natural language commands.

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

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

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TL;DR

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

The Census bureau MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to Census Bureau data resources. It provides structured and secure access to a wide range of U.S. demographic, business, and community datasets, so your agent can retrieve population statistics, analyze survey results, fetch business patterns, and explore census variables on your behalf.

  • Retrieve up-to-date population estimates: Have your agent pull the latest demographic and population data for specific states, counties, or cities using the Population Estimates Program (PEP).
  • Analyze American Community Survey results: Access detailed ACS 1-year and 5-year estimates for any geography, helping you understand community trends, housing, and economic data.
  • Explore business statistics by region: Automatically fetch County Business Patterns (CBP) and Annual Business Survey (ABS) data to examine local industry and employment trends.
  • Access decennial census data: Let your agent retrieve variables and statistics from the decennial census by vintage and dataset for deep historical and demographic analysis.
  • Investigate variable metadata and definitions: Effortlessly obtain detailed information about any census variable, including descriptions, data types, and valid values for more informed analysis.

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 Census bureau 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 Census bureau 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: ['census_bureau']
    }
);

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

Configure the agent with the MCP URL

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

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

Geocode Address

Tool to geocode a single address to get latitude/longitude coordinates.

Geocode Address for Census Geographies

Geocode an address and return Census geography identifiers including state, county, tract, block group, and block FIPS codes.

Geocode Address Parts

Tool to geocode an address using separate components (street, city, state, ZIP) to get latitude/longitude coordinates.

Geocode Address with Geography

Tool to geocode an address and return both coordinates and Census geography information.

Geocode Coordinates

Reverse geocode latitude/longitude coordinates to Census geographic areas.

Geocode Puerto Rico Address with Geography

Tool to geocode a Puerto Rico address and return coordinates plus Census geography data.

Batch Geocode Addresses with Geographies

Batch geocode multiple addresses from a CSV file and return Census geography codes.

Geocode Puerto Rico Address

Tool to geocode a Puerto Rico address with urbanization to latitude/longitude coordinates.

Get ACS 1-Year Estimates

Tool to retrieve 1-year American Community Survey (ACS) estimates for a specified geography.

Get ACS 5-Year Estimates

Retrieve 5-year American Community Survey (ACS) estimates from the U.

Get Community Resilience Estimates

Retrieve U.

Get County Business Patterns

Tool to retrieve County Business Patterns (CBP) data for a specified year.

Get Dataset Examples HTML

Tool to retrieve example queries for a Census dataset in HTML format.

Get Dataset Examples JSON

Tool to retrieve example API query patterns for a specific Census dataset and vintage.

Get Dataset Examples (XML)

Tool to retrieve example queries for a Census Bureau dataset in XML format.

Get Dataset Geography HTML

Tool to retrieve available geographies for a Census dataset in HTML format.

Get Dataset Geography JSON

Tool to get the list of supported geography levels for a specific Census dataset with their hierarchy and required predicates.

Get Dataset Geography XML

Tool to retrieve available geographies for a Census Bureau dataset in XML format.

Get Dataset Groups

Tool to retrieve the list of table groups for a Census dataset and vintage.

Get Dataset Sorts

Tool to list available sort options for a specific Census dataset and vintage.

Get Dataset Tags

Tool to list available tags/keywords for a specific Census dataset and vintage.

Get Dataset Variables JSON

Tool to retrieve the complete list of available variables for a specific Census dataset.

Get Decennial Census Data

Retrieve Decennial Census data (population, demographics, housing) from the U.

Get Planning Database Data

Get Planning Database (PDB) data containing Census tract and block group level data useful for planning.

Get Population Estimates

Retrieves Population Estimates Program (PEP) data from the US Census Bureau API.

Get TIGERweb ACS Generalized Boundaries

Tool to access generalized ACS (American Community Survey) boundary services from TIGERweb for specific survey years (2012-2024).

Get TIGERweb Map Service Metadata

Tool to retrieve TIGERweb MapServer service metadata including available layers, capabilities, and spatial reference information.

Get Timeseries Examples HTML

Tool to retrieve HTML-formatted example queries for a Census Bureau timeseries dataset.

Get Timeseries Examples JSON

Tool to get example queries for a timeseries dataset in JSON format.

Get Timeseries Examples XML

Tool to retrieve example queries for a Census Bureau timeseries dataset in XML format.

Get Timeseries Geography HTML

Tool to retrieve available FIPS geographies for a timeseries dataset in HTML format.

Get Timeseries Geography JSON

Tool to get available geographies for a timeseries dataset in JSON format.

Get Timeseries Geography XML

Tool to retrieve available geographies for a Census Bureau timeseries dataset in XML format.

Get Timeseries Variables HTML

Tool to retrieve a list of available variables for a Census timeseries dataset in HTML format.

Get Timeseries Variables JSON

Tool to get a list of variables available for a timeseries dataset in JSON format.

Get Timeseries Variables XML

Tool to get a list of variables available for a timeseries dataset in XML format.

Get Variable Details

Tool to retrieve metadata for a specific variable in a Census dataset for a given year.

List Available Datasets

Lists all available Census Bureau datasets with their metadata, vintages, and API endpoints.

List Datasets HTML

Tool to retrieve a complete HTML listing of all available (non-timeseries) Census Bureau datasets.

List Datasets XML

Tool to retrieve a list of all available Census Bureau datasets in XML format.

List Geocoder Benchmarks

List all available benchmark versions for the Census Bureau geocoding service.

List Geocoder Vintages

Tool to list available geography vintages for a given Census geocoder benchmark.

List TIGERweb Services

Tool to discover all available TIGERweb map services for Census geographic boundaries.

List Timeseries Datasets (HTML)

Tool to retrieve a list of all available timeseries datasets from the US Census Bureau API in HTML format.

List Timeseries Datasets (JSON)

Tool to list all available timeseries datasets from the US Census Bureau API.

List Timeseries Datasets (XML)

Tool to retrieve a list of all available Census Bureau timeseries datasets in XML format.

Query ACS Supplemental Estimates

Query ACS Supplemental Estimates data by variables and geography.

Query ACS Comparison Profiles

Query ACS Comparison Profiles data by variables and geography.

Query ACS Migration Flows

Tool to query American Community Survey (ACS) Migration Flows data by variables and geography.

Query ACS Data Profile

Tool to query ACS Data Profiles by variables and geography.

Query ACS Selected Population Profiles

Tool to query ACS Selected Population Profiles (SPP) data by variables and geography for specific population groups.

Query ACS Subject Tables

Tool to query ACS Subject Tables data by variables and geography.

Query Annual Business Survey

Tool to query Annual Business Survey Company Summary (abscs) data with demographic filters.

Query Commodity Flow Survey

Query Commodity Flow Survey data on freight shipments by origin, destination, mode, and commodity.

Query CPS Survey Data

Tool to query Current Population Survey (CPS) microdata including basic monthly employment data and supplemental surveys.

Query Decennial DHC

Tool to query Decennial Census Demographic and Housing Characteristics (DHC) data by variables and geography.

Query Decennial Census Demographic Profile

Tool to query Decennial Census Demographic Profile data by variables and geography.

Query Decennial Census P.L. Redistricting Data

Tool to query Decennial Census P.

Query Economic Census Data

Tool to query Economic Census data including establishments, employment, payroll, and receipts by geography and industry (NAICS).

Query International Trade Timeseries

Tool to query International Trade timeseries data from Census Bureau API.

Query Nonemployer Statistics

Tool to query Nonemployer Statistics data covering businesses with no paid employees.

Query PEP CharAgeGroups

Query population estimates by age groups, sex, race, and Hispanic origin from the Census Bureau PEP CharAgeGroups dataset.

Query PEP Components

Query components of population change from the Census Bureau Population Estimates Program (PEP).

Query PEP Housing Estimates

Query housing unit estimates from the US Census Bureau Population Estimates Program (PEP).

Query Population Projections

Query population projections from the Census Bureau API.

Query Surname Data

Query surname frequency data from the U.

Query TIGERweb Layer

Tool to query TIGERweb GeoServices for Census geographic boundaries and features.

Query Business Dynamics Statistics

Query Business Dynamics Statistics (BDS) time series data from the Census Bureau.

Query Timeseries Data

Query Census timeseries datasets containing longitudinal data for multiple time periods.

Query Economic Indicators Time Series

Tool to query Economic Indicators Time Series (EITS) data from the US Census Bureau.

Query Residential Construction Stats

Tool to query Residential Construction statistics from Census Bureau Economic Indicators Time Series (EITS).

Query Residential Sales Data

Query Residential Sales statistics from Census Bureau's Economic Indicator Time Series (EITS).

Query Health Insurance Estimates

Query Small Area Health Insurance Estimates (SAHIE) from the Census Bureau timeseries API.

Query Household Pulse Survey Timeseries

Tool to query Household Pulse Survey (HPS) timeseries data measuring household experiences during the COVID-19 pandemic.

Query International Database

Query International Database (IDB) demographic data for 227 countries and areas worldwide.

Query Timeseries International Trade Exports by HS

Tool to query international trade exports by Harmonized System code from Census Bureau time series API.

Query Timeseries International Trade Imports by End Use

Query international trade imports by end-use category from Census Bureau timeseries data.

Query Timeseries Poverty

Query poverty statistics from the Census Bureau's timeseries poverty datasets.

Query QWI Timeseries Data

Query Quarterly Workforce Indicators (QWI) timeseries data on employment, earnings, and job flows.

Query Timeseries QWI State/Area

Query Quarterly Workforce Indicators (QWI) State/Area characteristics from the Census Bureau's time series API.

Query ZIP Business Patterns

Tool to query ZIP Code Business Patterns (ZBP) data including establishments and employment by ZIP code and industry.

FRAMEWORKS

How to build Census bureau MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Census bureau MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Census bureau MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Census bureau MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Census bureau MCP with Claude Cowork

Codex logo

Codex

Use Census bureau MCP with Codex

OpenClaw logo

OpenClaw

Use Census bureau MCP with OpenClaw

Hermes logo

Hermes

Use Census bureau MCP with Hermes

CLI logo

CLI

Use Census bureau MCP with CLI

Google ADK logo

Google ADK

Use Census bureau MCP with Google ADK

Vercel AI SDK logo

Vercel AI SDK

Use Census bureau MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Census bureau MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Census bureau MCP with LlamaIndex

CrewAI logo

CrewAI

Use Census bureau MCP with CrewAI

FAQ

Frequently asked questions

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

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

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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.

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