How to integrate Census bureau MCP with LlamaIndex

This guide walks you through connecting Census bureau to LlamaIndex 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 LlamaIndex 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.

Census bureau logoCensus bureau
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 LlamaIndex 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 LlamaIndex 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.

Also integrate Census bureau with

TL;DR

Here's what you'll learn:
  • Set your OpenAI and Composio API keys
  • Install LlamaIndex and Composio packages
  • Create a Composio Tool Router session for Census bureau
  • Connect LlamaIndex to the Census bureau MCP server
  • Build a Census bureau-powered agent using LlamaIndex
  • Interact with Census bureau through natural language

What is LlamaIndex?

LlamaIndex is a data framework for building LLM applications. It provides tools for connecting LLMs to external data sources and services through agents and tools.

Key features include:

  • ReAct Agent: Reasoning and acting pattern for tool-using agents
  • MCP Tools: Native support for Model Context Protocol
  • Context Management: Maintain conversation context across interactions
  • Async Support: Built for async/await patterns

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 you begin, make sure you have:
  • Python 3.8/Node 16 or higher installed
  • A Composio account with the API key
  • An OpenAI API key
  • A Census bureau account and project
  • Basic familiarity with async Python/Typescript
2

Getting API Keys for OpenAI, Composio, and Census bureau

OpenAI API key (OPENAI_API_KEY)
  • Go to the OpenAI dashboard
  • Create an API key if you don't have one
  • Assign it to OPENAI_API_KEY in .env
Composio API key and user ID
  • Log into the Composio dashboard
  • Copy your API key from Settings
    • Use this as COMPOSIO_API_KEY
  • Pick a stable user identifier (email or ID)
    • Use this as COMPOSIO_USER_ID
3

Installing dependencies

npm install @composio/llamaindex @llamaindex/openai @llamaindex/tools @llamaindex/workflow dotenv

Create a new Typescript project and install the necessary dependencies:

  • @composio/llamaindex: Composio's LlamaIndex integration
  • @llamaindex/openai: OpenAI LLM integration
  • @llamaindex/tools: MCP client for LlamaIndex
  • @llamaindex/workflow: Workflow framework for LlamaIndex
  • dotenv: Environment variable management
4

Set environment variables

bash
OPENAI_API_KEY=your-openai-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id

Create a .env file in your project root:

These credentials will be used to:

  • Authenticate with OpenAI's GPT-5 model
  • Connect to Composio's Tool Router
  • Identify your Composio user session for Census bureau access
5

Import modules

import "dotenv/config";
import readline from "node:readline/promises";
import { stdin as input, stdout as output } from "node:process";

import { Composio } from "@composio/core";

import { mcp } from "@llamaindex/tools";
import { agent as createAgent } from "@llamaindex/workflow";
import { openai } from "@llamaindex/openai";

dotenv.config();

Create a new file called census bureau_llamaindex_agent.ts and import the required modules:

Key imports:

  • dotenv.config loads .env at runtime
  • readline gives us a simple CLI chat loop
  • Composio is the main Composio SDK client
  • mcp connects to an MCP endpoint
  • createAgent builds a LlamaIndex agent
  • openai configures the LLM backend
6

Load environment variables and initialize Composio

const OPENAI_API_KEY = process.env.OPENAI_API_KEY;
const COMPOSIO_API_KEY = process.env.COMPOSIO_API_KEY;
const COMPOSIO_USER_ID = process.env.COMPOSIO_USER_ID;

if (!OPENAI_API_KEY) throw new Error("OPENAI_API_KEY is not set");
if (!COMPOSIO_API_KEY) throw new Error("COMPOSIO_API_KEY is not set");
if (!COMPOSIO_USER_ID) throw new Error("COMPOSIO_USER_ID is not set");

What's happening:

This ensures missing credentials cause early, clear errors before the agent attempts to initialise.

7

Create a Tool Router session and build the agent function

async function buildAgent() {

  console.log(`Initializing Composio client...${COMPOSIO_USER_ID!}...`);
  console.log(`COMPOSIO_USER_ID: ${COMPOSIO_USER_ID!}...`);

  const composio = new Composio({
    apiKey: COMPOSIO_API_KEY,
    provider: new LlamaindexProvider(),
  });

  const session = await composio.create(
    COMPOSIO_USER_ID!,
    {
      toolkits: ["census_bureau"],
    },
  );

  const mcpUrl = session.mcp.url;
  console.log(`Composio Tool Router MCP URL: ${mcpUrl}`);

  const server = mcp({
    url: mcpUrl,
    clientName: "composio_tool_router_with_llamaindex",
    requestInit: {
      headers: {
        "x-api-key": COMPOSIO_API_KEY!,
      },
    },
    // verbose: true,
  });

  const tools = await server.tools();

  const llm = openai({ apiKey: OPENAI_API_KEY, model: "gpt-5" });

  const agent = createAgent({
    name: "composio_tool_router_with_llamaindex",
        description : "An agent that uses Composio Tool Router MCP tools to perform actions.",
    systemPrompt:
      "You are a helpful assistant connected to Composio Tool Router."+
"Use the available tools to answer user queries and perform Census bureau actions." ,
    llm,
    tools,
  });

  return agent;
}

What's happening here:

  • We create a Composio client using your API key and configure it with the LlamaIndex provider
  • We then create a tool router MCP session for your user, specifying the toolkits we want to use (in this case, census bureau)
  • The session returns an MCP HTTP endpoint URL that acts as a gateway to all your configured tools
  • LlamaIndex will connect to this endpoint to dynamically discover and use the available Census bureau tools.
  • The MCP tools are mapped to LlamaIndex-compatible tools and plug them into the Agent.
8

Create an interactive chat loop

async function chatLoop(agent: ReturnType<typeof createAgent>) {
  const rl = readline.createInterface({ input, output });

  console.log("Type 'quit' or 'exit' to stop.");

  while (true) {
    let userInput: string;

    try {
      userInput = (await rl.question("\nYou: ")).trim();
    } catch {
      console.log("\nAgent: Bye!");
      break;
    }

    if (!userInput) {
      continue;
    }

    const lower = userInput.toLowerCase();
    if (lower === "quit" || lower === "exit") {
      console.log("Agent: Bye!");
      break;
    }

    try {
      process.stdout.write("Agent: ");

      const stream = agent.runStream(userInput);
      let finalResult: any = null;

      for await (const event of stream) {
        // The event.data contains the streamed content
        const data: any = event.data;

        // Check for streaming delta content
        if (data?.delta) {
          process.stdout.write(data.delta);
        }

        // Store final result for fallback
        if (data?.result || data?.message) {
          finalResult = data;
        }
      }

      // If no streaming happened, show the final result
      if (finalResult) {
        const answer =
          finalResult.result ??
          finalResult.message?.content ??
          finalResult.message ??
          "";
        if (answer && typeof answer === "string" && !answer.includes("[object")) {
          process.stdout.write(answer);
        }
      }

      console.log(); // New line after streaming completes
    } catch (err: any) {
      console.error("\nAgent error:", err?.message ?? err);
    }
  }

  rl.close();
}

What's happening:

  • We're creating a direct terminal interface to chat with Census bureau
  • The LLM's responses are streamed to the CLI for faster interaction.
  • The agent uses context to maintain conversation history
  • The agent processes the request, selects appropriate Census bureau tools, and returns a result
  • We extract the answer from the result data structure and display it to the user
  • You can type 'quit' or 'exit' to stop the chat loop gracefully
  • Agent responses and any errors are streamed in a clear, readable format
9

Define the main entry point

async function main() {
  try {
    const agent = await buildAgent();
    await chatLoop(agent);
  } catch (err) {
    console.error("Failed to start agent:", err);
    process.exit(1);
  }
}

main();

What's happening here:

  • We're orchestrating the entire application flow
  • The agent gets built with proper error handling
  • Then we kick off the interactive chat loop so you can start talking to Census bureau
10

Run the agent

npx ts-node llamaindex-agent.ts

When prompted, authenticate and authorise your agent with Census bureau, then start asking questions.

Complete Code

Here's the complete code to get you started with Census bureau and LlamaIndex:

import "dotenv/config";
import readline from "node:readline/promises";
import { stdin as input, stdout as output } from "node:process";

import { Composio } from "@composio/core";
import { LlamaindexProvider } from "@composio/llamaindex";

import { mcp } from "@llamaindex/tools";
import { agent as createAgent } from "@llamaindex/workflow";
import { openai } from "@llamaindex/openai";

dotenv.config();

const OPENAI_API_KEY = process.env.OPENAI_API_KEY;
const COMPOSIO_API_KEY = process.env.COMPOSIO_API_KEY;
const COMPOSIO_USER_ID = process.env.COMPOSIO_USER_ID;

if (!OPENAI_API_KEY) {
    throw new Error("OPENAI_API_KEY is not set in the environment");
  }
if (!COMPOSIO_API_KEY) {
    throw new Error("COMPOSIO_API_KEY is not set in the environment");
  }
if (!COMPOSIO_USER_ID) {
    throw new Error("COMPOSIO_USER_ID is not set in the environment");
  }

async function buildAgent() {

  console.log(`Initializing Composio client...${COMPOSIO_USER_ID!}...`);
  console.log(`COMPOSIO_USER_ID: ${COMPOSIO_USER_ID!}...`);

  const composio = new Composio({
    apiKey: COMPOSIO_API_KEY,
    provider: new LlamaindexProvider(),
  });

  const session = await composio.create(
    COMPOSIO_USER_ID!,
    {
      toolkits: ["census_bureau"],
    },
  );

  const mcpUrl = session.mcp.url;
  console.log(`Composio Tool Router MCP URL: ${mcpUrl}`);

  const server = mcp({
    url: mcpUrl,
    clientName: "composio_tool_router_with_llamaindex",
    requestInit: {
      headers: {
        "x-api-key": COMPOSIO_API_KEY!,
      },
    },
    // verbose: true,
  });

  const tools = await server.tools();

  const llm = openai({ apiKey: OPENAI_API_KEY, model: "gpt-5" });

  const agent = createAgent({
    name: "composio_tool_router_with_llamaindex",
    description:
      "An agent that uses Composio Tool Router MCP tools to perform actions.",
    systemPrompt:
      "You are a helpful assistant connected to Composio Tool Router."+
"Use the available tools to answer user queries and perform Census bureau actions." ,
    llm,
    tools,
  });

  return agent;
}

async function chatLoop(agent: ReturnType<typeof createAgent>) {
  const rl = readline.createInterface({ input, output });

  console.log("Type 'quit' or 'exit' to stop.");

  while (true) {
    let userInput: string;

    try {
      userInput = (await rl.question("\nYou: ")).trim();
    } catch {
      console.log("\nAgent: Bye!");
      break;
    }

    if (!userInput) {
      continue;
    }

    const lower = userInput.toLowerCase();
    if (lower === "quit" || lower === "exit") {
      console.log("Agent: Bye!");
      break;
    }

    try {
      process.stdout.write("Agent: ");

      const stream = agent.runStream(userInput);
      let finalResult: any = null;

      for await (const event of stream) {
        // The event.data contains the streamed content
        const data: any = event.data;

        // Check for streaming delta content
        if (data?.delta) {
          process.stdout.write(data.delta);
        }

        // Store final result for fallback
        if (data?.result || data?.message) {
          finalResult = data;
        }
      }

      // If no streaming happened, show the final result
      if (finalResult) {
        const answer =
          finalResult.result ??
          finalResult.message?.content ??
          finalResult.message ??
          "";
        if (answer && typeof answer === "string" && !answer.includes("[object")) {
          process.stdout.write(answer);
        }
      }

      console.log(); // New line after streaming completes
    } catch (err: any) {
      console.error("\nAgent error:", err?.message ?? err);
    }
  }

  rl.close();
}

async function main() {
  try {
    const agent = await buildAgent();
    await chatLoop(agent);
  } catch (err: any) {
    console.error("Failed to start agent:", err?.message ?? err);
    process.exit(1);
  }
}

main();

Conclusion

You've successfully connected Census bureau to LlamaIndex through Composio's Tool Router MCP layer. Key takeaways:
  • Tool Router dynamically exposes Census bureau tools through an MCP endpoint
  • LlamaIndex's ReActAgent handles reasoning and orchestration; Composio handles integrations
  • The agent becomes more capable without increasing prompt size
  • Async Python provides clean, efficient execution of agent workflows
You can easily extend this to other toolkits like Gmail, Notion, Stripe, GitHub, and more by adding them to the toolkits parameter.
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.

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. LlamaIndex 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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