Metadata is the listing copy, categories, and keywords a retailer uses to show your book to readers. Good metadata is the single highest-leverage thing you can do for a self-published book after the cover. This article covers each field retailers care about and how to write them well.

Description

The description is your pitch. It appears on the product page, in retailer search results, and in most book discovery tools. KDP allows up to 4,000 characters, Apple allows up to 4,000, Kobo allows 5,000. Use the space, but not aimlessly.

A strong description is three parts:

1. Hook. One to two sentences. The reader knows whether to keep reading based on these alone.
2. Premise. Three to five sentences. Who the protagonist is, what they want, what's in their way. No plot twists. No third-act reveals.
3. Proof. One or two sentences. Comp titles, review pull quotes, awards, or a one-liner from a respected reader.

Length: 800 to 1,500 characters is a sweet spot. Much longer and readers skim. Much shorter and it looks thin.

Formatting

KDP allows:

• Bold (<b>...</b>)
• Italic (<i>...</i>)
• Paragraph breaks (<p>...</p> or blank lines)
• Line breaks (<br>)
• Bullet lists (<ul><li>...</li></ul>)

Other retailers accept the same subset. Don't try to use CSS or images; they're stripped.

What not to do

• Don't describe the cover ("A striking red cover..."). Readers can see it.
• Don't open with an in-world quote from the book. Readers skip them.
• Don't tell the plot chronologically. Start with tension, not setup.
• Don't use "In a world where..." for anything. It reads as a parody of itself now.

AI Assistant help

From Publish → Metadata → Description, click Draft with assistant. The assistant uses your manuscript, comp titles, and genre to propose a description. Treat the output as a first draft, not final copy. Edit it in your voice.

Categories

Categories are where your book lives on the retailer's shelf. Getting the right categories is worth more than most authors realise; it's how casual browsers find you.

How many

• KDP. Up to 2 via metadata. You can request up to 10 more via Amazon's KDP support (manual process, takes a week).
• Apple Books. Up to 2.
• Kobo. Up to 3.

Picking categories

• Go deep, not wide. "Mystery" is 50,000+ books. "Cozy Mystery → Culinary" is a few hundred. Ranking on a narrow list puts you on the front page of that list.
• Match the book. A "Thriller" with a romance subplot is not a "Romance." Pick where your core reader will look.
• Be honest. Retailers penalise miscategorisation with lower visibility, not bans, but the effect is real.

Tool

From Publish → Metadata → Categories, click Browse by genre. Bellwether shows the retailer's live category tree filtered by your language. Pick from the tree.

Keywords

Keywords are search terms. On KDP, you get seven. On Apple Books and Kobo, you get more (15 and unlimited respectively), but the first seven matter most.

What works

• Specific reader searches. "Small town romance with a grumpy single dad." Not "romance book."
• Trope names. "Enemies to lovers." "Found family." "Fated mates." Readers search by trope.
• Comp author phrases. "Fans of Tana French" works in some retailers' search; check current policy.
• Setting and era. "Victorian London mystery." "1920s Paris."

What doesn't

• Your book's title or subtitle (already indexed)
• Your author name (already indexed)
• "Bestseller," "award-winning," etc. (against policy; may trigger review)
• Other authors' names directly (also against policy in most retailers)
• Generic single words ("mystery," "romance," "thriller")

Tool

From Publish → Metadata → Keywords, you get a textbox that accepts up to seven phrases, comma-separated. Below it, a Suggestions panel lists trending keywords for your category that you might be missing.

ISBN

• Own ISBN. Purchased from your country's ISBN authority (Bowker in the US, Nielsen in the UK, etc.). One ISBN per edition (ebook, paperback, hardcover each get their own).
• KDP-assigned ISBN. Free, but only valid on KDP. You can't use it on other retailers, and KDP is listed as the publisher.

If you plan to distribute to multiple retailers, buy your own ISBNs. If you're KDP-exclusive, KDP-assigned is fine.

Enter ISBNs under Publish → Metadata → ISBN. Bellwether validates the format. If you entered a wrong digit, save will fail until you fix it.

Series

If your book is part of a series, enter:

• Series title. "Maren Chronicles"
• Position. 1, 2, 3 (integers only on KDP; Apple accepts decimals for novellas like 1.5)
• Reading order. On standalone-friendly series, set Can be read standalone to yes so retailers know they can feature individual books.

Retailers with series logic (KDP especially) link books in the same series so readers who finish one get pointed to the next.

Publication date

• First publication. The original publication date. If you released earlier on another retailer, use that date, not today's.
• This edition. The date this specific edition went live. KDP will assign this automatically when the book publishes.

Backdating is allowed if you're moving a previously self-published book to a new retailer. Don't backdate to try to game "new releases" lists; retailers are aware of the trick.

A/B testing metadata

Established authors routinely A/B test description and keyword changes. You can't do this natively on retailers (they don't expose A/B tools), but you can test iteratively:

1. Live with your initial metadata for 2–4 weeks.
2. Note your baseline sales and rank.
3. Change one thing (description, keyword 1, or top category).
4. Wait another 2–4 weeks.
5. Compare.

Change one variable at a time or you can't tell what moved the needle. Bellwether's metadata history (under Publish → Metadata → History) logs every change with a timestamp so you can correlate against sales dates in your royalty dashboard.

Description HTML cheat sheet

For copy-pasting into the description field:

<b>Bold text</b>
<i>Italic text</i>
<p>A new paragraph.</p>
<br>Line break without a new paragraph.
<ul>
  <li>Bullet one</li>
  <li>Bullet two</li>
</ul>

These are the only tags KDP consistently renders. Avoid headings, divs, spans, or styled elements; they're stripped.

Internationalisation

If you publish in multiple languages (original plus translations), each translation needs its own metadata. Bellwether creates a separate book record per language by default.

The translated description needs to be in the target language. Running it through an AI translator is acceptable for first draft but review by a native speaker is recommended before publishing.

Common edge cases

Amazon showed a different description than I uploaded. KDP strips unsupported HTML. Re-submit with plain text, bold, italic, and paragraph breaks only.

My categories are "wrong" on Amazon. Amazon assigns the two you chose, plus up to three more algorithmically based on content. You can request changes by contacting KDP support.

I want to add more keywords than seven. Seven is the indexed limit. You can add more context to the description and categories instead; both feed the search algorithm.

Keywords that trigger policy review. Anything implying a ranking ("bestseller"), using another author's name, or claiming awards you didn't win will flag KDP's review. Remove and resubmit.

My book appears under the wrong category on retailer. Contact the retailer directly; category corrections are usually manual. Bellwether can't change the retailer's assignment after submission.