ai-agents-vertex-ai-tool-schem-litellm-proxy-receives-tool-definitions-with-empty-752b71e2

THEN Ensure every tool definition sent to LiteLLM has parameters set to an object with type: 'object' and properties: {} (empty). Alternatively, set parameters to None. This replicates Gemini's strict schema requirement. Also verify that drop_params: true does not fix this issue; downgrading to LiteLLM 1.80.10.rc.5 may serve as a temporary workaround until the provider sanitization patch is released.

```python
tools = [
    {
        'type': 'function',
        'function': {
            'name': 'list_calendars',
            'description': '...',
            'parameters': {}  # or None
        }
    }
]
```