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ontology_spec

Category: Engineering  ·  Sub-category: architecture  ·  Last updated:
Write and maintain an ontology-based design-doc set (ONTOLOGY.md + CRITERIA.md + RATIONALE.md + ARCHITECTURE_LOG.md, plus DYNAMICS.md for games) instead of a single SPEC.md. ONTOLOGY is the implementation reference — purpose, entities as structs, invariants, rules as short pseudocode, commands and events, numbers — with provenance tags ([D]/[P]/[T]) and Serves tags; CRITERIA turns every rule into input → expect rows, each owning a test directory; RATIONALE records the why of current decisions with alternatives and evidence; ARCHITECTURE_LOG holds the dated history. Use when starting a new app, game, or major system, when converting an existing SPEC.md into this format, when the user says "ontology", "/ontology_spec", or asks for design docs where the *why* matters. Also use for a teleology review (does each thing still do what it's for?).
Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

A design-doc set that separates what exists and how it behaves (ONTOLOGY), how we know it's right (CRITERIA), why each choice was made (RATIONALE), and how it got here (ARCHITECTURE_LOG). For games and other systems with emergent behavior, add why it's fun / why it works (DYNAMICS).

What this skill does

ontology_spec is a community-contributed Claude Code skill in the architecture sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/ontology-spec/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when starting a new app, game, or major system, when converting an existing SPEC.md into this format, when the user says "ontology", "/ontology_spec", or asks for design docs where the *why* matters.

Who uses this skill

The ontology_spec Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/ontology-spec
curl -L https://claudskills.com/skills/ontology-spec/SKILL.md \
  -o ~/.claude/skills/ontology-spec/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/ontology-spec/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/ontology-spec/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\ontology-spec\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the ontology_spec Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/ontology-spec/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the ontology_spec skill do?
Write and maintain an ontology-based design-doc set (ONTOLOGY.md + CRITERIA.md + RATIONALE.md + ARCHITECTURE_LOG.md, plus DYNAMICS.md for games) instead of a single SPEC.md. ONTOLOGY is the implementation reference — purpose, entities as structs, invariants, rules as short pseudocode, commands and events, numbers — with provenance tags ([D]/[P]/[T]) and Serves tags; CRITERIA turns every rule into input → expect rows, each owning a test directory; RATIONALE records the why of current decisions with alternatives and evidence; ARCHITECTURE_LOG holds the dated history. Use when starting a new app, game, or major system, when converting an existing SPEC.md into this format, when the user says "ontology", "/ontology_spec", or asks for design docs where the *why* matters. Also use for a teleology review (does each thing still do what it's for?).
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the ontology_spec skill?
Use ontology_spec when your Claude Code task falls under the Engineering category — specifically in the architecture area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use ontology_spec" or describe the task and let Claude pick). Browse related skills at /category/engineering/.
What is a Claude Code skill and how does the ontology_spec skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. ontology_spec is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
roby2358. (2026). ontology_spec [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/ontology-spec/
BibTeX
@misc{ontology-spec-2026,
  author    = {roby2358},
  title     = {ontology_spec [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/ontology-spec/}
}

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Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

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