1. Outline control
A book tool should let you shape the structure before generating thousands of words. Check whether chapters can be added, removed, reordered and rewritten without starting over.
2. Long-document consistency
Ask how the tool keeps names, definitions, arguments and tone consistent across chapters. Generate a test section and look for repetition or contradictions before committing to a full manuscript.
3. Editing workflow
Generation speed matters less if every correction requires a complete regeneration. Look for section-level editing, targeted rewrites and a clear way to preserve approved text.
4. Source handling and fact checking
If you are writing nonfiction, check whether the tool can work from your own references and whether you can trace important claims back to a source. AI fluency is not evidence.
5. Export quality
Know the required destination first: PDF lead magnet, EPUB, Word document, Kindle workflow or print layout. A tool that cannot export cleanly into your publishing path may create extra work at the end.
6. Commercial rights
Read the current license. Confirm whether you can sell the output, use it for clients, publish under your own brand and reuse generated assets. Do not assume all AI-writing products grant the same rights.
7. Total cost
The sticker price may not include model credits, external API charges, image generation, formatting or publishing tools. Compare the full workflow cost instead of the first checkout price.
8. Human contribution
The strongest use of AI is usually acceleration, not replacement. A useful book needs selection, judgment, examples, evidence and editing. If the tool encourages you to skip those steps, faster generation may reduce quality rather than improve productivity.