Three fields, three jobs
A Google Play listing for a website app is mostly the same listing any app gets, and it is written in three fields with very different purposes. The title (30 characters) is the app's name plus, if it fits, one phrase saying what it is. The short description (80 characters) is the line under the screenshots that decides whether someone taps "Read more"; it is also shown in search results. The full description (4,000 characters) is what Play indexes for search and what a careful buyer reads before installing.
The checker counts each against its limit as you type and runs the copy past the parts of Play's metadata policy that catch website apps most often.
What Play's metadata policy actually bans
- Promotional words in the title and short description — "free", "best", "#1", "top", "new", "sale", "download now". Play's own examples. They are fine in the full description.
- Emoji, emoticons and decorative symbols anywhere in the title or short description; repeated punctuation ("!!!") too.
- Capitalisation for emphasis. A brand written in caps is allowed; a WORD shouted for effect is not.
- Ranking and performance claims — "most downloaded", "fastest".
- Testimonials and star ratings quoted in the description.
- Keyword stuffing — lists of search terms, or the same phrase repeated until the text reads like a tag cloud.
Violations are usually a rejection with a note, not a ban, but each costs a review cycle. The checker's warnings map to these items; a warning means "Play may push back", which for a first submission is reason enough to reword.
Writing the listing for a website app
Reviewers and buyers both ask the same question of an app that wraps a site: why not just use the website? The description should answer it in the first paragraph. Name the things the app does that the browser tab does not — a home-screen icon, push notifications for order updates, an offline menu, a login that stays signed in, native tabs. If the honest answer is "nothing yet", that is also the answer to why Play's minimum functionality review may reject it; the policy guide explains what to add.
Keywords, without stuffing
Play's search ranks the title highest, the short description next and the full description after that. One natural mention of a term in each place is roughly all the credit you can get; a tenth mention earns nothing and reads as stuffing. The coverage table shows where each of your target phrases appears so you can place them once and stop. Write for the person deciding whether to install, and the search engine will follow.