The first clue, "Pen", opens the board with intentional ambiguity. In Pinpoint, a single clue rarely proves the category — it is a starting hypothesis, not a verdict.
"Sword" narrows the field. A valid category must explain both "Pen" and "Sword" with the same rule — not two separate stories.
By "Iceberg", the category "Things that are associated with tips" should start to feel inevitable. Three clues with one rule beats three clues with three excuses.
"Advice column" adds another member of the same set. Each new row should strengthen "Things that are associated with tips", not send you hunting for a new theme.
"High-quality service" is the stress test. If "Things that are associated with tips" still fits naturally here, the puzzle is solved; if not, your category is too narrow or too broad.
Read together, "Pen", "Sword", "Iceberg", "Advice column", and "High-quality service" converge on "Things that are associated with tips". That convergence — one precise category, five varied clues — is the structure Pinpoint rewards.