document-comparison

name	document-comparison
description	Compare two or more PDF documents by extracting targeted sections, building a structured comparison matrix, and highlighting differences with page references.

Document comparison skill.

When to activate

Use this skill when the user asks you to:

• Compare two or more PDF documents
• Find differences between document versions
• Compare terms, clauses, or sections across documents
• Build a side-by-side comparison of document contents

Methodology

1. Identify the documents

List available files and confirm which documents to compare. If the user is vague ("compare the two contracts"), list the PDFs and ask which ones they mean.

2. Extract metadata for both documents

Call extract_pdf_metadata on each document to get:

• Page count
• Title and author
• Creation and modification dates

This helps you understand the scope and identify if one is a revision of the other (same title, different dates).

3. Determine comparison dimensions

Use the think tool to decide what to compare. Common dimensions:

• Structure: sections, headings, page count
• Content: specific clauses, terms, definitions
• Numbers: financial figures, dates, quantities
• Coverage: topics present in one but missing in the other

Ask the user what matters most if it is not clear from context.

4. Targeted extraction

Extract the relevant sections from each document. Use page ranges to keep extractions focused:

• For structural comparison: extract the first 2-3 pages (table of contents, introduction) from each
• For clause comparison: extract the specific pages containing the target clauses
• For full comparison of short docs (< 20 pages): extract all

5. Build the comparison matrix

Use the think tool to construct a comparison. Structure it as:

| Dimension      | Document A (page) | Document B (page) | Difference |
|----------------|--------------------|--------------------|------------|
| Term length    | 12 months (p.3)    | 24 months (p.4)    | B is 2x    |
| Payment terms  | Net 30 (p.5)       | Net 60 (p.5)       | B is longer |

For numerical differences, use the calculator to compute deltas and percentages.

6. Present findings

Structure the comparison report as:

1. Overview: what was compared, document metadata
2. Key differences: the most significant changes, ordered by impact
3. Detailed comparison: the full matrix with page references
4. Summary: a plain-language summary of the differences

MUST

• Always extract metadata before content
• Always include page references for every cited fact
• Use the think tool to plan the comparison dimensions
• Use the calculator for any numerical comparisons (deltas, percentages)
• Present differences in a structured table format

MUST NOT

• Compare documents without reading both -- never assume content
• Fabricate page numbers or content not in the extracted text
• Extract entire large documents when targeted extraction will do
• Present opinions about which document is "better" unless asked
• Skip the metadata step -- it reveals version relationships