With regards to performance review comments, it helps to be as specific and actionable as possible. Somewhat similar to SMART goal construction, when you're leaving comments for your employees you need to be objective.
SMART: Specific, Measurable, Achievable, Relevant, Time-bound
Give specific examples or reasoning behind your thoughts or score selections. Additionally, follow this through when making suggestions for improvement.
As an example:
Alex, I think you did a fantastic job managing the team over the past quarter. You really brought them all together to execute those five projects for your clients. Notably, you did really well communicating with your group - bringing them together in meetings to realign, when needed. This was certainly a factor in you guys getting all the work done ahead of schedule. Please keep this up as we head into this next quarter. There's a lot coming up and the team can really learn from your natural ability to rally the troops!
Zooming out quickly, the whole point of performance evaluations is that they're meant to be a tool by which employees can learn and develop. As this is the case, the traditional "annual" review has become outdated and out-of-touch with modern work timelines and an increasingly young workforce.
Annual reviews incur recency bias and other knowledge gaps that prevent us from properly communicating effective strategies for employees to take. This is why specificity is so important - and perhaps increasing the cadence of reviews is as well.