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 dylantarre/animation-principles --skill naturalistic-motiongit clone --depth 1 https://github.com/dylantarre/animation-principlesWrote 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/dylantarre/animation-principles/naturalistic-motion)<a href="https://agentmods.dev/skills/dylantarre/animation-principles/naturalistic-motion"><img src="https://agentmods.dev/badge/skills/dylantarre/animation-principles/naturalistic-motion/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/dylantarre/animation-principles/naturalistic-motion"><img src="https://agentmods.dev/badge/skills/dylantarre/animation-principles/naturalistic-motion.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk 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 | $0.00036 | $0.00799 |
| Opus 5 | $0.00018 | $0.00400 |
| Sonnet 5 | $0.00007 | $0.00160 |
| Haiku 4.5 | $0.00004 | $0.00080 |
Grade A, and why
naturalistic-motion 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 12d 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 — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Naturalistic Motion
Think like a biologist watching life unfold. Nothing in nature moves mechanically. Everything breathes, adjusts, responds. Life is continuous subtle motion.
Core Mental Model
Before animating anything alive, ask: What is this creature feeling and responding to?
Living things are never truly still. They shift weight, breathe, notice, adjust. Naturalistic motion isn't about copying reality—it's about capturing aliveness.
The 12 Principles Through Organic Life
Secondary Action — Life is layered motion. While a character talks, they breathe. While they breathe, they blink. While they blink, their weight shifts. Stack subtle actions.
Follow Through & Overlapping Action — Bodies are systems of connected parts. Movement cascades through joints and soft tissue. Nothing moves in isolation.
Arcs — Nature abhors straight lines. Every joint creates rotation. Every movement traces curves. Study the path of a hand gesture—it's never linear.
Slow In & Slow Out — Organic motion accelerates and decelerates continuously. Muscles engage and release. This is what makes movement look "alive" rather than robotic.
Timing — Life has varied timing. Quick glances, slow stretches, medium walks. The diversity of speeds creates believable organism behavior.
Squash & Stretch — Flesh is malleable. Skin wrinkles, muscles bulge, fat jiggles. Even subtle squash and stretch sells organic tissue.
Anticipation — Living things telegraph intention. Watch a cat before it pounces. The body organizes itself before action. Include preparatory micro-movements.
Solid Drawing — Anatomy matters. Understand skeletal structure, muscle groups, and how they connect. Organic motion respects physical construction.
Appeal — Naturalistic doesn't mean realistic. Appealing organic motion is idealized life—the essence of a cat, not a veterinary diagram.
Exaggeration — Subtle exaggeration. Naturalistic motion pushes organic qualities just 10-20% past reality. Enough to read clearly, not enough to break believability.
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.
- 12d ago First seen · 78 lines · 36 tokens per session scan A c18097773ddb
naturalistic-motion is a skill published in the GitHub repository dylantarre/animation-principles (81 stars, last pushed 8mo ago), licensed MIT. It adds 36 tokens to every session and 799 once invoked, about $0.0002 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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