If the transcript clearly reflects an institution-wide or formally available pass-fail policy, you usually do not need to write a separate explanation unless the application specifically asks for context.

The key is transparency. Report your GPA and transcript exactly as required. A short explanation can make sense when the semester looks unusual and the reason is not obvious from the record itself.

Avoid turning a normal policy choice into a long defense. If asked, explain the timing and policy in one or two factual sentences, then move back to the broader academic and professional evidence in your profile.

Focus on what recruiting can verify: later grades, quantitative coursework, internships, and interview performance. Those signals are more useful than trying to litigate one semester in advance.

If the transcript already labels the semester pass/fail, I would not over-explain it.