mcp-tool-definition-sani-vertex-ai-returns-400-error-functiondeclaration-pa-e30e6420

THEN Ensure all tool definitions sent to LiteLLM for Gemini/Vertex AI have either 'parameters': None (if no parameters) or 'parameters': {"type":"object","properties":{}} (if parameters are empty). This prevents Vertex AI from rejecting the function declaration.

Instead of:
{
  'type': 'function',
  'function': {
    'name': 'list_calendars',
    'description': '...',
    'parameters': {}
  }
}
Use:
{
  'type': 'function',
  'function': {
    'name': 'list_calendars',
    'description': '...',
    'parameters': None
  }
}
or explicitly:
{
  'type': 'function',
  'function': {
    'name': 'list_calendars',
    'description': '...',
    'parameters': {
      'type': 'object',
      'properties': {}
    }
  }
}