Tool calls don't work with Claude models

[filiptrplan]

Try to get Claude to call a tool, it doesn't provide it with any parameters. Gemini 2.5 Pro seems to work.

Claude output:

    {
      "role": "assistant",
      "content": "I'll use the first tool to get the current time in your timezone. Since you haven't specified your exact timezone, I'll use Europe/Ljubljana as that appears to be your local timezone based on available information.",
      "tool_calls": [
        {
          "function": {
            "name": "tool_get_current_time_post"
          },
          "id": "toolu_vrtx_01Vgv1fSDRJi6ovtff5koBeX",
          "index": 0,
          "type": "function"
        }
      ]
    },

Gemini 2.5 Pro:

    {
      "role": "assistant",
      "content": "Okay, I will call the first tool to get the current time. Since you haven't specified a timezone, I'll use 'Europe/Ljubljana' as a default.",
      "tool_calls": [
        {
          "function": {
            "arguments": "{\"timezone\":\"Europe/Ljubljana\"}",
            "name": "tool_get_current_time_post"
          },
          "id": "call_MHw4aHFZaW5BRnNBNkdSMUw1SUQ",
          "index": 0,
          "type": "function"
        }
      ]
    }

Claude doesn't provide an arguments or parameters key no matter how I prompt it. Is that a limitation in the API? It seems to receive the tools okay.