Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add magnus919/agent-skills --skill epubgit clone --depth 1 https://github.com/magnus919/agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/magnus919/agent-skills/epub)<a href="https://agentmods.dev/skills/magnus919/agent-skills/epub"><img src="https://agentmods.dev/badge/skills/magnus919/agent-skills/epub/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/magnus919/agent-skills/epub"><img src="https://agentmods.dev/badge/skills/magnus919/agent-skills/epub.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00105 | $0.04282 |
| Opus 5 | $0.00053 | $0.02141 |
| Sonnet 5 | $0.00021 | $0.00856 |
| Haiku 4.5 | $0.00011 | $0.00428 |
Grade A, and why
epub scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 382 lines — stays where its author put it; the contents beside it link to each section on GitHub.
EPUB — Ebook Creation, Extraction & Enrichment
Expert-level EPUB handling: read, write, edit, validate, and extract knowledge from EPUB 2 and EPUB 3 files. Ships with five Python CLI scripts and five detailed references covering the entire EPUB domain.
When not to use
- Non-EPUB documents — Word, PDF, plain markdown, or web-page conversion tasks do not match any script here; route them to a document-handling skill instead of forcing an EPUB tool onto a non-EPUB file.
- DRM-locked ebooks — these scripts read and write standard OCF/EPUB containers; they do not remove or bypass digital rights management.
- Mobi/AZW/Kindle-native formats — use a dedicated converter first; this skill neither reads nor writes Amazon-proprietary containers.
EPUB Format Essentials
An EPUB file is a ZIP archive (Open Container Format, OCF) with a specific internal layout. The W3C EPUB 3.3 standard uses a "three planes" model:
| Plane | Contains | Key Rule |
|---|---|---|
| Manifest | All resources (XHTML, images, CSS, fonts) | Every file must be listed in OPF <manifest> |
| Spine | Linear reading order | Only XHTML/SVG by default; other types need fallbacks |
| Content | Resources embedded within documents | Core media types guaranteed; foreign types need fallbacks |
The package document (content.opf) holds metadata (Dublin Core), manifest
(every resource), and spine (reading order). EPUB3 uses an XHTML nav document
for navigation; EPUB2 uses .ncx XML. Both can coexist for compatibility.
Critical rules: mimetype must be the first ZIP entry, stored uncompressed.
All content documents must be well-formed XML (XHTML, not HTML5). The manifest
must list every file used in rendering. Read references/epub-format-internals.md
for the full structure reference.
Decision Table — Which Script to Use
| Task | Script | Notes |
|---|---|---|
| See structure, metadata, manifest, spine, TOC | epub-info |
JSON output, --summary for compact |
| Extract clean reading-order text | epub-text |
Per-chapter or single file |
| Create minimal valid EPUB from scratch | epub-scaffold |
No dependencies needed |
| Extract facts, quotes, definitions, arguments | epub-extract-knowledge |
Heuristic or LLM mode (env var auto-detect) |
| Validate against EPUB spec | epub-validate |
EPUBCheck or Python fallback |
| Edit EPUB (metadata, chapters, spine, CSS) | epub-edit |
v2 flagship — 8 subcommands, non-intrusive |
| Extract images | epub-images |
List or extract to directory |
| Batch process multiple EPUBs | epub-batch |
Wrap existing scripts across globs |
| Convert EPUB2 → EPUB3 | epub-convert |
Add NAV, update NS, keep NCX |
| Diagnose & repair structural issues | epub-repair |
Auto-fix common validation failures |
What ships with it
24 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- evals/evals.json 7.8 KB
- README.md 1.7 KB
- references/accessibility.md 3.8 KB
- references/agent-capability-discovery.md 6.7 KB
- references/apple-books-compatibility.md 5.0 KB
- references/epub-format-internals.md 7.2 KB
- references/fixed-layout-epub.md 2.8 KB
- references/llm-config-and-extraction.md 3.4 KB
- references/media-overlays.md 3.5 KB
- references/python-libraries.md 11 KB
- references/spec-and-validation.md 4.8 KB
- references/tutorials-and-guides.md 6.4 KB
- scripts/epub-batch 5.9 KB
- scripts/epub-convert 5.6 KB
- scripts/epub-cover 4.8 KB
- scripts/epub-edit 18 KB
- scripts/epub-extract-knowledge 14 KB
- scripts/epub-images 4.4 KB
- scripts/epub-info 6.5 KB
- scripts/epub-repair 13 KB
- scripts/epub-scaffold 9.5 KB
- scripts/epub-text 5.9 KB
- scripts/epub-validate 12 KB
- scripts/test_epub_skill.sh 21 KB runs code
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 7d ago Changed · +2 lines · +16 tokens per session cc5bb93f16e0
- 11d ago First seen · 380 lines · 89 tokens per session scan A f6e4a2d4c378
epub is a skill published in the GitHub repository magnus919/agent-skills (76 stars, last pushed today), licensed MIT. It adds 105 tokens to every session and 4,282 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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