Skip to main content

Lab 11: Building a "Global Market Analyst" Challenge

Goal​

In this lab, you will build an agent that can retrieve live currency exchange rates from a public REST API. You will learn how to use the OpenAPIToolset to automatically generate the necessary tools from an OpenAPI specification.

Step 1: Create the Agent Project​

We will continue using the modern uv workflow.

  1. Initialize the project:

    uv init market_analyst --python 3.10
    cd market_analyst
    uv add "google-adk>=2.1.0" python-dotenv

  2. Set up your API key in the .env file for the Gemini model. (The Frankfurter Currency API we are using is completely free and requires no authentication).

Step 2: Define the OpenAPI Specification​

Exercise: Open agent.py. A skeleton for the OpenAPI specification is provided below. Your task is to complete the spec for the /latest endpoint's get operation. You can deduce the necessary parameters from the Frankfurter API documentation (or the theory section).

# In agent.py
import json
from google.adk import Agent
from google.adk.tools.openapi_tool import OpenAPIToolset

# ============================================================================
# OPENAPI SPECIFICATION
# ============================================================================
# The `operationId` is critical. The ADK uses it to generate the tool's name
# (e.g., `operationId: "get_latest_rates"` becomes the `get_latest_rates` tool).

FRANKFURTER_SPEC = {
    "openapi": "3.0.0",
    "info": {
        "title": "Frankfurter Currency API",
        "description": "Free API for current and historical foreign exchange rates",
        "version": "1.0.0"
    },
    "servers": [{"url": "https://api.frankfurter.dev/v1"}],
    "paths": {
        "/latest": {
            "get": {
                # TODO: Complete this section for the "/latest" endpoint.
                # - The operationId should be "get_latest_rates".
                # - The summary should be "Get latest exchange rates".
                # - It needs a "parameters" list with query parameters: "amount", "from", "to".
            }
        }
    }
}

# ============================================================================
# AGENT NODE DEFINITION
# ============================================================================

# TODO: 1. Create the OpenAPIToolset instance.
# TODO: 2. Define the root Agent node and register the toolset.
root_agent = Agent(...)

Step 3: Run and Test Your Agent​

  1. Start the agent in terminal mode: 
    uv run adk run .
  2. Interact with the agent:
    • Test its capabilities:
      • "Convert 100 USD to EUR."
      • "How many Japanese Yen (JPY) can I get for 50 British Pounds (GBP)?"
      • "Convert 500 AUD to USD and EUR." (Notice if it calls the API twice or handles it smartly!)
    • Observe the logs to see the agent constructing and executing the HTTP requests perfectly based on your spec.

Having Trouble?​

If you get stuck, you can find the complete, working code in the lab-solution.md file.

Lab Summary​

You have successfully integrated a live REST API into your agent without writing a single manual tool function. You have learned:

  • How to translate API documentation into an OpenAPI specification.
  • How to use OpenAPIToolset to automatically generate tools from a spec.
  • How to instruct your agent to use the new, auto-generated tools.

Self-Reflection Questions​

  • What are the main advantages of using OpenAPIToolset compared to writing a custom Python function (like requests.get(...)) for each API endpoint?
  • The operationId in the OpenAPI spec is very important. What do you think would happen if two different paths in the spec had the same operationId?
  • Many modern web services publish their own OpenAPI specifications (often as a URL like api.example.com/openapi.json). How does this widespread adoption of the OpenAPI standard make it easier to build powerful, integrated AI agents?

🕵️ Hidden Solution 🕵️​

Looking for the solution? Here's a hint (Base64 decode me): L2RvYy1hZGstdHJhaW5pbmcvbW9kdWxlMTEtb3BlbmFwaS10b29scy9sYWItc29sdXRpb24=

The direct link is: Lab Solution