When providing feedback on student writing, you will want to address higher- and lower-order concerns.
Higher-order concerns are concerns with the presentation of the information:
Clear focus or thesis
Attention to audience, purpose, and writing situation
Logical paragraph and essay structure
Support / evidence for the information
Logical conclusions based on evidence and analysis
Often, these concerns will be heavily weighted on your rubric because these areas represent the content, structure, and organization of the information. As such, you will want to make sure that your feedback in these areas is thorough, especially in the final comment.
Lower-order concerns are issues with the readability of the information:
Grammar and punctuation
Sentence structure and parallelism
Clarity and conciseness of language
Editing, proofreading, and spell-checking errors
Bean, J. C. (2011). Engaging ideas: The professor's guide to integrating writing, critical thinking, and active learning in the classroom. 2nd ed. Jossey-Bass.
Responding to student writing--principles and practices. (2016). Center for Research on Learning and Teaching. University of Michigan.
Sommers, N. (2013). Responding to student writers. Bedford/St. Martin's.