Summary
For a specified tool name, returns the default value of the desired parameter.
Syntax
GetParameterValue (tool_name, index)
| Parameter | Explanation | Data Type | 
tool_name  | The tool name for which the parameter default value will be returned.  | String | 
index  | Index position of the parameter in the specified tool's parameter list.  | Integer | 
| Data Type | Explanation | 
| String | Returns the default value of the specified parameter for the tool.  | 
Code sample
Returns the default value for specified tool parameter.
import arcpy
# Returns 'POLYGON'
print(arcpy.GetParameterValue("CreateFeatureClass_management", 2))