The defining criterion for a muqaddimat al-ʿilm is:
مَا يَتَوَقَّفُ عَلَيْهِ الشُّرُوعُ فِي مَسَائِلِهِ
Matters on which entering the problems of a science depends.
The word shuruʿ refers to beginning the study of the science's problems. It identifies prerequisite ideas, not every detail that the reader will eventually learn.
For example, an initial grasp of situational requirements and the correspondence of speech to them can prepare a student for the detailed issues of Maʿani.