A review comment should help the author understand what needs attention and why. Point to a specific behavior, risk, or maintainability concern instead of leaving a vague reaction on a line of code.
Make the reasoning visible
- Describe the scenario where the current code could fail or confuse a future maintainer.
- Separate a required correctness or safety change from an optional style suggestion.
- Ask a question when you lack context instead of assuming the author's intent.
Offer a path forward
When useful, suggest an alternative or a test that would resolve the concern. Keep the requested change proportional to its impact; do not make a personal preference a release blocker.
Review the full change, not only the diff decoration. If an issue is important enough to block merging, summarize it clearly so the author can find the remaining work.