Tool Calling

The Infron supports OpenAI-compatible function calling, allowing models to call tools and functions. This follows the same specification as the OpenAI Function Calling API.

Basic tool calls

Python

import os
from openai import OpenAI
 
client = OpenAI(
    api_key='<API_KEY>',
    base_url='https://llm.onerouter.pro/v1'
)
 
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'],
                        'description': 'The unit for temperature'
                    }
                },
                'required': ['location']
            }
        }
    }
]
 
completion = client.chat.completions.create(
    model='claude-sonnet-4-5@20250929',
    messages=[
        {
            'role': 'user',
            'content': 'What is the weather like in San Francisco?'
        }
    ],
    tools=tools,
    tool_choice='auto',
    stream=False,
)
 
print('Assistant:', completion.choices[0].message.content)
print('Tool calls:', completion.choices[0].message.tool_calls)

TypeScript

Controlling tool selection: By default, tool_choice is set to 'auto', allowing the model to decide when to use tools. You can also:

• Set to 'none' to disable tool calls

• Force a specific tool with: tool_choice: { type: 'function', function: { name: 'your_function_name' } }

Tool call response format

When the model makes tool calls, the response includes tool call information:

{
  "id": "msg_bdrk_01C8nvCh9VwSAnSuZZG1crX3",
  "choices": [
    {
      "finish_reason": "tool_calls",
      "index": 0,
      "logprobs": null,
      "message": {
        "content": "",
        "refusal": null,
        "role": "assistant",
        "annotations": null,
        "audio": null,
        "function_call": null,
        "tool_calls": [
          {
            "id": "toolu_bdrk_01MDzkbNZ7Vw6UQ51uEB9LbB",
            "function": {
              "arguments": "{\"location\":\"San Francisco, CA\"}",
              "name": "get_weather"
            },
            "type": "function"
          }
        ]
      }
    }
  ],
  "created": 1771655880,
  "model": "claude-sonnet-4-5@20250929",
  "object": "chat.completion",
  "service_tier": null,
  "system_fingerprint": null,
  "usage": {
    "completion_tokens": 56,
    "prompt_tokens": 615,
    "total_tokens": 671,
    "completion_tokens_details": null,
    "prompt_tokens_details": {
      "audio_tokens": null,
      "cached_tokens": null
    },
    "input_tokens": 0,
    "output_tokens": 0,
    "server_tool_use": {
      "web_search_requests": ""
    },
    "ttft": 0
  }
}

Next steps

Tool Calling