feat: Update PythonCodeStructuredTool.py

[YamonBot]

You can specify the variables to be used in the tool in the Data format, without needing to explain a separate signature, and directly input the description.

[aws-amplify-sa-east-1[bot]]

This pull request is automatically being deployed by Amplify Hosting (learn more).

Access this pull request here: https://pr-2977.dmtpw4p5recq1.amplifyapp.com

[YamonBot]

The description field is automatically generated by understanding the signature of the selected method and is passed in the BaseModel format to the arg_schema field of the tool. Global values are Data objects, and the values of these fields function like global variables in the respective tool.