Hello there! Based on your need for a report card comment generator, I'd recommend using MagicSchool AI. This tool acts like a helpful teacher's assistant, offering over 40 different tools that simplify various tasks for educators.

One of its key features is the Advanced Proofreading tool, which identifies writing issues in students' assignments and offers constructive feedback. While it's not explicitly stated that it generates report card comments, this feature could potentially be used to provide pre-written comments based on student performance and behavior.

Moreover, MagicSchool AI also offers a Content Generation feature that allows for the quick creation of original, standards-aligned educational content. This could be useful in crafting personalized comments for each student.

Please note that while MagicSchool AI seems to be the closest match to your needs, it might not fully cover the specific functionality of generating report card comments. However, its suite of tools designed specifically for educational needs could be a valuable addition to your teaching toolkit.