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Posted on • Originally published at buywhere.ai

Build an AI Shopping Agent with OpenAI Agents SDK + BuyWhere MCP

#openai #agentsdk #mcp #tutorial

In this tutorial, you'll build an AI shopping agent that searches products, compares prices across retailers, and finds deals — all using natural language. We'll use:

  • OpenAI Agents SDK — the official framework for building agentic AI apps
  • BuyWhere MCP Server — a Model Context Protocol server that provides real-time product search and price comparison across 50M+ products

Prerequisites

  • Node.js 18+
  • An OpenAI API key (with access to the Agents SDK)
  • A BuyWhere API key (free at https://buywhere.ai)

Step 1: Set up the project 

mkdir shopping-agent
cd shopping-agent
npm init -y
npm install openai-agents @buywhere/mcp-server
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Step 2: Configure environment

Create a .env file:

OPENAI_API_KEY=sk-...
BUYWHERE_API_KEY=bw_...
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Step 3: Create the shopping agent

Create index.ts:

import { Agent, Runner } from "openai-agents";
import { createBuyWhereMCPServer } from "@buywhere/mcp-server";
import dotenv from "dotenv";

dotenv.config();

async function main() {
  // Connect BuyWhere MCP as a tool for the agent
  const buywhere = await createBuyWhereMCPServer({
    apiKey: process.env.BUYWHERE_API_KEY!,
  });

  const agent = new Agent({
    name: "Shopping Agent",
    instructions: `You are a helpful shopping assistant. Use the BuyWhere 
      MCP tools to search for products, compare prices, and find deals. 
      Always show prices in SGD and include the retailer name.`,
    tools: [...buywhere.getTools()],
  });

  const result = await Runner.run(agent, {
    input: "Find the best price for Sony WH-1000XM6 headphones in Singapore",
  });

  console.log(result.output);
}

main().catch(console.error);
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Step 4: Run it 

npx tsx index.ts
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Example output:

Here are the best prices for Sony WH-1000XM6 headphones in Singapore:

1. **Amazon SG** — SGD 398 (free shipping)
2. **Shopee SG** — SGD 429 (with voucher: SGD 399)
3. **Lazada SG** — SGD 449 (Lazada Bonus: SGD 419)
4. **Challenger** — SGD 459

**Best deal:** Amazon SG at SGD 398 — save SGD 61 vs retail price.
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How It Works

The OpenAI Agents SDK manages the agent lifecycle — reasoning, tool selection, and response generation. BuyWhere MCP provides the product data layer:

  1. User asks a natural language question
  2. The agent decides which BuyWhere tool to call
  3. BuyWhere searches across retailers and returns structured product data
  4. The agent synthesizes the results into a human-readable answer

Going Further

Add more capabilities:

// Price drop alerts
agent.addTool({
  name: "track_price",
  description: "Track price changes for a product",
  parameters: {
    productUrl: { type: "string" },
    targetPrice: { type: "number" },
  },
  execute: async ({ productUrl, targetPrice }) => {
    return buywhere.createPriceAlert(productUrl, targetPrice);
  },
});
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Resources

BuyWhere — Compare prices across 20+ retailers. Save money. Shop smarter.

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