# 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](https://platform.openai.com/docs/guides/function-calling).

### **Basic tool calls**

{% tabs %}
{% tab title="Python" %}

```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)
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
import OpenAI from 'openai';
 
const openai = new OpenAI({
  '<API_KEY>',
  baseURL: 'https://llm.onerouter.pro/v1',
});
 
const tools: OpenAI.Chat.Completions.ChatCompletionTool[] = [
  {
    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'],
      },
    },
  },
];
 
const completion = await openai.chat.completions.create({
  model: 'anthropic/claude-sonnet-4.5',
  messages: [
    {
      role: 'user',
      content: 'What is the weather like in San Francisco?',
    },
  ],
  tools: tools,
  tool_choice: 'auto',
  stream: false,
});
 
console.log('Assistant:', completion.choices[0].message.content);
console.log('Tool calls:', completion.choices[0].message.tool_calls);
```

{% endtab %}
{% endtabs %}

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:

```json
{
  "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

{% content-ref url="<https://app.gitbook.com/s/Z9C9AjT7j46HAcQrOVWw/features/tool-calling>" %}
[Tool Calling](https://app.gitbook.com/s/Z9C9AjT7j46HAcQrOVWw/features/tool-calling)
{% endcontent-ref %}


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