Metadata extraction

Skill brege/dewey-decimal-skill/skills/metadata-extraction

Extract author, title, year, and contributor metadata from ebook files (EPUB, PDF). Use when you need to identify a book's bibliographic information from its embedded metadata or filename.From its SKILL.md

Install

npx -y skills add brege/dewey-decimal-skill --skill metadata-extraction

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

2 things to look at

1 stars1 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.
runs commandsInstructs the agent to run 3 commands, including `unzip -p "$file" META-INF/container.xml | grep -oP 'full-path="\K[^"]*'` and 2 more.

SKILL.md

3.2 KB, 800 tokens by cl100k_base, as published. Nobody here has run it

Metadata Extraction

Extract bibliographic metadata from ebook files.

Priority Order

EPUB OPF metadata (most authoritative)
PDF document properties
Filename parsing (least reliable)
User input (for disambiguation only)

EPUB Extraction

Step 1: Find OPF Path

unzip -p "$file" META-INF/container.xml | grep -oP 'full-path="\K[^"]*'

Returns path like OEBPS/content.opf or content.opf.

Step 2: Extract Metadata

unzip -p "$file" "$opf_path" | grep -E '<dc:(creator|title|date|contributor)'

Fields

Tag	Content
`<dc:creator>`	Author name(s)
`<dc:title>`	Book title
`<dc:date>`	Publication date (extract YYYY)
`<dc:contributor opf:role="trn">`	Translator
`<dc:contributor opf:role="edt">`	Editor

PDF Extraction

pdfinfo "$file" 2>/dev/null | grep -E '^(Title|Author|CreationDate|ModDate):'

Extract:

Title field
Author field
CreationDate year (format: D:YYYYMMDDhhmmss)

Filename Parsing

Parse for hints when metadata insufficient:

Author: Often at start, before dash or title
Title: Main text
Year: Four digits in parentheses or at end

Example: Charles.Bukowski.-.Love.Is.A.Dog.From.Hell.2007.RETAIL.EPUB.eBook-CTO.epub

Author: Charles Bukowski
Title: Love Is A Dog From Hell
Year: 2007

Year Rules

Use publication year of THIS edition, not original work.

Aristotle's Nicomachean Ethics (ancient) with Irwin translation (2019): use 2019
Marx's Capital originally 1867: use edition's publication year
If EPUB date differs from original work date, prefer EPUB date

Useless Metadata

Some EPUBs have placeholder or garbage metadata. Treat these as missing:

Title: [No data], Unknown, Untitled, empty
Author: Unknown, Anonymous (unless actually anonymous work), empty
Date: Only modification date present, no publication date

When OPF metadata is useless, fall back to filename parsing immediately.

Author Name Normalization

Fix common capitalization issues from metadata:

Harold Mcgee → Harold McGee (fix surname caps)
CHARLES BUKOWSKI → Charles Bukowski (fix all-caps)
Preserve intentional lowercase particles: de Beauvoir, van Gogh

Use opf:file-as attribute if present - it often has correct citation format:

<dc:creator opf:file-as="McGee, Harold">Harold Mcgee</dc:creator>

Translator Verification

Translator info in filenames is often wrong or refers to different editions.

Verify translator matches publisher/edition (e.g., Penguin 2004 Marx = Fowkes, not Guyer-Wood)
If translator not in metadata, check ISBN against known editions
When uncertain, ask user

Missing Data

When metadata genuinely unavailable:

No author: Ask user
No year: Ask user for "publication year of this edition"
Ambiguous title: Ask user
No translator but work is translated: Ask user or look up by ISBN/publisher

Do not guess. Do not proceed without author and title.

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.