Tool Calling

What is Tool Calling?

• Allows LLMs to interact with other systems

• Supported by most of the newest LLMs, but not all

• Sounds complicated? Scary? It’s not too bad, actually…

Reference: https://jcheng5.github.io/llm-quickstart/quickstart.html#/how-it-works

How it does NOT work

How it DOES work

Demo: Weather R

library(httr)
library(ellmer)
library(dotenv)

# Load environment variables
load_dot_env()

# Define weather function
get_weather <- function(latitude, longitude) {
  base_url <- "https://api.open-meteo.com/v1/forecast"

  tryCatch(
    {
      response <- GET(
        base_url,
        query = list(
          latitude = latitude,
          longitude = longitude,
          current = "temperature_2m,wind_speed_10m,relative_humidity_2m"
        )
      )
      rawToChar(response$content)
    },
    error = function(e) {
      paste("Error fetching weather data:", e$message)
    }
  )
}

# Create chat instance
chat <- chat_openai(
  model = "gpt-4.1",
  system_prompt = "You are a helpful assistant that can check the weather. Report results in imperial units."
)

# Register the weather tool
#
# Created using `ellmer::create_tool_def(get_weather)`
chat$register_tool(tool(
  get_weather,
  "Fetches weather information for a specified location given by latitude and
longitude.",
  latitude = type_number(
    "The latitude of the location for which weather information is requested."
  ),
  longitude = type_number(
    "The longitude of the location for which weather information is requested."
  )
))

# Test the chat
chat$chat("What is the weather in Seattle?")

Demo: Weather Python

import requests
from chatlas import ChatAnthropic
from dotenv import load_dotenv

load_dotenv()  # Loads OPENAI_API_KEY from the .env file

# Define a simple tool for getting the current weather
def get_weather(latitude: float, longitude: float):
    """
    Get the current weather for a location using latitude and longitude.
    """
    base_url = "https://api.open-meteo.com/v1/forecast"
    params = {
        "latitude": latitude,
        "longitude": longitude,
        "current": "temperature_2m,wind_speed_10m,relative_humidity_2m",
    }

    try:
        response = requests.get(base_url, params=params)
        response.raise_for_status()  # Raise an exception for bad status codes
        return response.text
    except requests.RequestException as e:
        return f"Error fetching weather data: {str(e)}"


chat = ChatAnthropic(
    model="claude-3-5-sonnet-latest",
    system_prompt=(
        "You are a helpful assistant that can check the weather. "
        "Report results in imperial units."
    ),
)

chat.register_tool(get_weather)
chat.chat("What is the weather in Seattle?")