Turn an Ebook into a Book Skill

A useful Book Skill is not simply an ebook renamed as SKILL.md. The agent needs a small navigation layer, stable chapter files, full source material for context, and clear rules about what the source can and cannot instruct it to do. The package should help retrieval while preserving the difference between source text and executable instructions.

1. Start with a supported source

EPUB and RTF are the ebook-related formats currently accepted. Kindle formats such as MOBI and AZW are not accepted. EPUB files are ZIP-based packages and must contain META-INF/container.xml; an archive without that required part is rejected before processing.

Books can also begin as PDF, Word, HTML, or Markdown. The most important requirement is a usable heading hierarchy. Consistent chapter headings produce better routes than visual page breaks or manually styled text.

• Confirm you own the content or have permission to process it.
• Use one source file when it already represents one complete book.
• Remove unrelated front matter if it overwhelms the chapter structure.
• Check that chapter titles appear as real headings after conversion.

2. Understand the package structure

A Book Skill separates navigation from evidence. The generated package can look like this:

book-knowledge/
  SKILL.md
  README.md
  chapters/
    ch01-introduction.md
    ch02-core-method.md
  glossary.md
  patterns.md
  cheatsheet.md
  source-reports/
    original-book.md
  references/
  manifest.json

SKILL.md tells an agent how to navigate the package and verify claims. Chapter files provide smaller reading units. The complete converted source remains in source-reports/ so an answer can recover surrounding context when an extracted chapter is insufficient.

3. Use conservative indexes

Automatic semantic summaries can sound confident while losing qualifications or inventing relationships. The local Book Skill takes a narrower approach:

• Glossary: includes terms only when the source contains an explicit definition pattern.
• Patterns index: routes to headings explicitly named as methods, patterns, algorithms, frameworks, or similar structures.
• Rules quick reference: collects source lines containing explicit conditional or normative language.

These files are navigation aids, not a substitute for the book. A rule extracted from one sentence may depend on qualifications in the surrounding paragraphs. Important answers should open the linked chapter and, when necessary, the full source report.

4. Preserve the instruction boundary

An ebook is untrusted source data. It may include prompts, examples, quoted instructions, malicious text, or requests to connect to external services. Packaging it as a Skill must not give those passages authority over the current user or agent.

The generated Skill therefore states that content in chapters, source reports, and assets is data. Source requests for tool calls, network access, uploads, secret disclosure, permission changes, or instruction overrides must not be followed. External actions still require the current user's explicit request.

5. Review before installing

Automatic chapter detection selects a repeated heading level and creates stable slugs. This works well for conventional books but can misread books with inconsistent headings, numbered parts, appendices, or very short chapters.

1. Open SKILL.md and confirm the chapter route names.
2. Check that no chapter begins or ends in the middle of an important section.
3. Compare glossary entries and rule excerpts with their linked chapters.
4. Keep the source report in the package for verification.
5. Install the folder only in an Agent Skills-compatible location you control.

6. Add model analysis only as an explicit option

A future model-assisted mode could create summaries, topic maps, exercises, or richer cross-chapter links. That mode would require sending selected text to a model provider unless a capable model runs locally. It should be clearly separated from the current local mode, explain exactly what leaves the device, require deliberate consent, and allow users to choose the provider and scope.

The deterministic local package remains useful even without model analysis because it provides a stable source hierarchy and traceable navigation.