Text tools
Most people counting text are counting against a specific ceiling, and the ceilings are not interchangeable. A meta description gets truncated by search engines somewhere around 155 to 160 characters. An SMS splits at 160. Academic abstracts are commonly capped at 250 or 300 words. Social platforms and ad formats each have their own limit. Knowing which one applies tells you whether to watch the word count or the character count.
Where it goes wrong is the assumption that a word count is an exact, universal number. It is not. Tools disagree over hyphenated compounds, standalone numerals, and text split across line breaks, so two honest counters can differ by a percent or two on the same passage. For a soft target that is irrelevant; for a hard cutoff that rejects your submission, leave yourself a margin and verify against the destination.
Worth knowing before you start, rather than after.