You can define functions that the model can call during the conversation. This enables the model to perform specific actions or retrieve information from external sources.

​
Basic Function Calling

Here’s how to implement function calling with the chat completions API: 
from openai import OpenAI

client = OpenAI(
    api_key="your_truefoundry_api_key",
    base_url="<truefoundry-base-url>/api/llm/api/inference/openai"
)

response = client.chat.completions.create(
    model="openai-main/gpt-4o-mini",
    messages=[{"role": "user", "content": "What's the weather in New York?"}],
    tools=[{
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "Get the current weather in a given location",
            "parameters": {
                "type": "object",
                "properties": {
                    "location": {
                        "type": "string",
                        "description": "The city and state, e.g. San Francisco, CA"
                    },
                    "unit": {
                        "type": "string",
                        "enum": ["celsius", "fahrenheit"]
                    }
                },
                "required": ["location"]
            }
        }
    }]
)

print(response.choices[0].message.tool_calls)

​
Function Definition Schema

When defining functions, you need to provide:
  • name: The name of the function
  • description: A clear description of what the function does
  • parameters: JSON Schema object describing the function parameters

​
Parameter Types

Functions support various parameter types: 
function_schema = {
    "name": "process_data",
    "description": "Process data with various parameters",
    "parameters": {
        "type": "object",
        "properties": {
            "text": {
                "type": "string",
                "description": "Text to process"
            },
            "count": {
                "type": "integer",
                "description": "Number of items to process"
            },
            "confidence": {
                "type": "number",
                "description": "Confidence threshold (0.0 to 1.0)"
            },
            "enabled": {
                "type": "boolean",
                "description": "Whether processing is enabled"
            },
            "categories": {
                "type": "array",
                "items": {"type": "string"},
                "description": "List of categories"
            }
        },
        "required": ["text"]
    }
}

​
Multiple Functions

You can define multiple functions for the model to choose from: 
tools = [
    {
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "Get current weather information",
            "parameters": {
                "type": "object",
                "properties": {
                    "location": {"type": "string"},
                    "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]}
                },
                "required": ["location"]
            }
        }
    },
    {
        "type": "function",
        "function": {
            "name": "search_web",
            "description": "Search the web for information",
            "parameters": {
                "type": "object",
                "properties": {
                    "query": {"type": "string"},
                    "max_results": {"type": "integer", "default": 5}
                },
                "required": ["query"]
            }
        }
    }
]

response = client.chat.completions.create(
    model="openai-main/gpt-4o-mini",
    messages=[{"role": "user", "content": "What's the weather in Paris and search for tourist attractions there?"}],
    tools=tools
)

​
Handling Function Calls

When the model decides to call a function, you’ll receive a tool_calls response: 
# Check if the model wants to call a function
if response.choices[0].message.tool_calls:
    for tool_call in response.choices[0].message.tool_calls:
        function_name = tool_call.function.name
        function_args = json.loads(tool_call.function.arguments)
        
        # Execute your function
        if function_name == "get_weather":
            result = get_weather(function_args["location"], function_args.get("unit", "celsius"))
        elif function_name == "search_web":
            result = search_web(function_args["query"], function_args.get("max_results", 5))
        
        # Send the function result back to the model
        messages.append({
            "role": "tool",
            "tool_call_id": tool_call.id,
            "content": str(result)
        })
        
        # Continue the conversation
        follow_up = client.chat.completions.create(
            model="openai-main/gpt-4o-mini",
            messages=messages
        )

​
Function Calling Control

You can control when and how functions are called:

​
Force Function Call

response = client.chat.completions.create(
    model="openai-main/gpt-4o-mini",
    messages=[{"role": "user", "content": "What's the weather?"}],
    tools=tools,
    tool_choice={"type": "function", "function": {"name": "get_weather"}}
)

​
Allow or Prevent Function Calls

# Allow automatic function calling (default)
tool_choice="auto"

# Prevent function calling
tool_choice="none"

# Force any function call
tool_choice="required"

​
Example: Complete Function Calling Workflow

import json
from openai import OpenAI

client = OpenAI(
    api_key="your_truefoundry_api_key",
    base_url="<truefoundry-base-url>/api/llm/api/inference/openai"
)

def get_weather(location, unit="celsius"):
    # Simulate weather API call
    return f"The weather in {location} is 22°C and sunny"

def complete_function_call_example():
    messages = [{"role": "user", "content": "What's the weather in Tokyo?"}]
    
    response = client.chat.completions.create(
        model="openai-main/gpt-4o-mini",
        messages=messages,
        tools=[{
            "type": "function",
            "function": {
                "name": "get_weather",
                "description": "Get current weather",
                "parameters": {
                    "type": "object",
                    "properties": {
                        "location": {"type": "string"},
                        "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]}
                    },
                    "required": ["location"]
                }
            }
        }]
    )
    
    # Handle function call
    if response.choices[0].message.tool_calls:
        messages.append(response.choices[0].message)
        
        for tool_call in response.choices[0].message.tool_calls:
            args = json.loads(tool_call.function.arguments)
            result = get_weather(args["location"], args.get("unit", "celsius"))
            
            messages.append({
                "role": "tool",
                "tool_call_id": tool_call.id,
                "content": result
            })
        
        # Get final response
        final_response = client.chat.completions.create(
            model="openai-main/gpt-4o-mini",
            messages=messages
        )
        
        return final_response.choices[0].message.content
    else:
        return response.choices[0].message.content

if __name__ == "__main__":
    print(complete_function_call_example())