Function Calling

Tool declaration

{
  "model": "deepseek-v4.1-flash",
  "messages": [
    {
      "role": "user",
      "content": "When is the Chandigarh office open?"
    }
  ],
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "get_office_hours",
        "description": "Look up the public opening hours for a supported office.",
        "parameters": {
          "type": "object",
          "properties": {
            "city": {
              "type": "string",
              "enum": [
                "Chandigarh",
                "London"
              ]
            }
          },
          "required": [
            "city"
          ],
          "additionalProperties": false
        }
      }
    }
  ],
  "tool_choice": "auto",
  "max_tokens": 512
}

Bounded tool loop

import json

hours = {"Chandigarh": "09:00-18:00", "London": "09:00-17:00"}
for _ in range(4):
    response = client.chat.completions.create(
        model="deepseek-v4.1-flash", messages=messages, tools=tools,
        tool_choice="auto", max_tokens=512,
    )
    message = response.choices[0].message
    messages.append(message.model_dump(exclude_none=True))
    if not message.tool_calls:
        print(message.content or "")
        break
    for call in message.tool_calls:
        args = json.loads(call.function.arguments)
        if (call.function.name != "get_office_hours"
                or not isinstance(args, dict)
                or not isinstance(args.get("city"), str)
                or args.get("city") not in hours):
            raise ValueError("Tool request is not allowed")
        messages.append({
            "role": "tool", "tool_call_id": call.id,
            "content": json.dumps({"hours": hours[args["city"]]}),
        })
else:
    raise RuntimeError("Tool-call budget exhausted")