mece-review: Claude Code skill for MECE (Mutually Exclusive, Collectively Exhaustive) review of documents, categories, and lists

SKILL.md

name	mece-review
description	Review a set of documents or categories for MECE (Mutually Exclusive, Collectively Exhaustive) overlap and gaps
argument-hint	<file-or-directory> [--strict]
allowed-tools	Read, Glob, Grep, Agent

MECE Review

Analyze a set of documents, categories, or organizational structures for MECE (Mutually Exclusive, Collectively Exhaustive) quality. Identify overlaps, gaps, and propose cleaner boundaries.

Background

MECE is the principle that items in a set should not overlap (mutually exclusive) and should cover the full space (collectively exhaustive). Both humans and LLMs struggle with MECE — it requires keeping multiple layers of context in mind and finding sharply defined boundaries even when they don't naturally exist.

True MECE is often unachievable. The practical goal is "semi-MECE": groupings that make sense to the audience, minimize overlap, and don't overload with too many fine-grained categories.

Step 1: Identify the scope

Parse $ARGUMENTS to determine what to review:

• If a directory: read all files and treat each as a category/document
• If a list of files: read each one
• If a single file with sections: treat each top-level section as a category
• If a list (bullet or enumerated): treat each item as a category and apply Step 4b

Step 2: Map content ownership

For each document or category, summarize:

• What it covers (its intended role)
• What audience need it serves
• Key topics and claims

Step 3: Identify overlaps

Find content that appears in more than one document/category:

• Same topic covered in multiple places with different framing
• Implementation details in a strategy document (or vice versa)
• Duplicate checklists, lists, or recommendations
• Two organizing principles that don't align

For each overlap, note:

• Which documents/categories are involved
• Whether the overlap is intentional (e.g., executive summary restating details) or accidental
• Which document should own the content

Step 4: Identify gaps

Check whether the full space is covered:

• Are there topics that belong in scope but aren't addressed anywhere?
• Are there categories that logically should exist but don't?

Step 4b: Review lists for MECE

Lists (bullet points and enumerated) are the most common MECE target. When reviewing a list, check:

Mutual exclusivity:

• Does any single item belong in two or more categories? If so, the categories overlap. Propose sharper boundary definitions or merge the overlapping items.
• Are items at the same level of abstraction? Mixing high-level ("Improve testing") with specific ("Add UUID validation test") in the same list signals a categorization problem.
• Do adjacent items cover the same ground with different wording? This is the most common list defect — two bullets that say the same thing slightly differently.

Collective exhaustiveness:

• Is there an obvious item missing? Read the list as a promise to the audience: does it cover the space they'd expect?
• Does the list's framing (title, lead-in sentence) imply coverage that the items don't deliver? A heading like "All security findings" with three bullets is a gap.

Ordering and grouping:

• Are items grouped by a consistent principle? (by priority, by phase, by component, by severity — pick one, not several)
• If the list is enumerated, does the numbering imply priority or sequence? If so, verify the order actually reflects that.
• Would subgroups with headings make the list clearer? A flat list of 13 items is harder to scan than 3 groups of 3-5.

Common list defects:

• Item that is really two items joined by "and" — split it
• Item that is a subset of another item — nest it or merge
• Item that restates the list's heading — remove it
• Inconsistent phrasing (some items are actions, others are states) — normalize

Step 5: Propose fixes

For each issue, propose a specific action:

• Trim: remove duplicated content from the non-owning document, add a cross-reference instead
• Move: relocate content to the document that should own it
• Bridge: add a brief note connecting related sections across documents
• Split: break a document that covers too much into focused pieces
• Merge: combine documents that cover the same ground

Output format

Present findings as:

1. Document roles — table showing each document's intended role and audience
2. Overlaps found — numbered list with specific sections and proposed fixes
3. Gaps found — what's missing from the overall coverage
4. What's well-placed — sections that are unique and correctly located (no changes needed)

If --strict flag is passed, treat any overlap as a problem. Otherwise, accept intentional cross-referencing (summaries restating details, etc.) as valid.

Principles

• The creativity in MECE is finding sharply defined boundaries — this is the hard part
• Keep the audience's cognitive load in mind — slightly impure MECE is better than too many fine-grained categories
• Flag overlaps but let the user decide — MECE is a quality bar, not a rigid rule
• When in doubt, propose cross-references rather than deletion