tools: prioritizes explicitly passed parameters over generated ones

[teocns]

Problem

weather_tool = cf.tool(
    name="get_current_weather",
    description="Get the current weather at a location",
    parameters={
        "type": "object",
        "properties": {
            "latitude": {
                "type": "number",
                "description": "The latitude of the location",
            },
            "longitude": {
                "type": "number",
                "description": "The longitude of the location",
            },
        },
        "required": ["latitude", "longitude"],
    },
    fn=get_current_weather,
)

TypeError: controlflow.tools.tools.Tool() got multiple values for keyword argument 'parameters'

Key changes

1. We now handle custom parameters first, before any description processing
2. Added a safety check if param.name not in parameters.get("properties", {}) to ensure we only try to add descriptions for parameters that exist in the schema
3. The rest of the function (return value handling, description length check, etc.) remains unchanged.

This way:

• Custom parameters are respected
• Parameter descriptions from annotations are still added when available
• The function remains backward compatible with all existing tests
• We avoid trying to add descriptions to parameters that don't exist in the schema

Tests

1. Basic custom parameters override - ensuring that provided parameters completely replace the generated ones
2. Annotation handling with custom parameters - verifying that parameter descriptions from annotations are still added when the parameter names match
3. Disabling parameter descriptions - confirming that include_param_descriptions=False works correctly with custom parameters