This PR makes it so if we receive a tool use from the model without any
corresponding text, we'll insert some placeholder text to keep the
conversation in a well-structured format.

This aims to fix an error that Antonio was seeing:


![image](https://github.com/user-attachments/assets/eeba95ef-9b67-41d7-bce3-afe84bcdc7b1)

Release Notes:

- N/A