medium-300-500ms

medium-300-500ms is a skill for Claude Code, Codex from dylantarre/animation-principles. It costs 32 tokens per session (714 once invoked), scanned A, original, MIT.

Guidance for standard animations lasting 300–500 milliseconds, including page transitions, major interface changes, and animated illustrations.

In plain words
What is it for?
Use it to design easing, key positions, deformation, follow-through, and multi-element motion in interfaces.
Why use it?
Meaningful motion needs enough time to be understood without interrupting the user's flow. This helps balance clarity with responsiveness.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to design easing, key positions, deformation, follow-through, and multi-element motion in interfaces.

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Install with agentmods
npx agentmods add skills/dylantarre/animation-principles/medium-300-500ms
Install

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.

Any agent
npx skills add dylantarre/animation-principles --skill medium-300-500ms
Clone the repo
git clone --depth 1 https://github.com/dylantarre/animation-principles

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for medium-300-500ms

README.md
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Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 714 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 18 Mar 2026
  • Snyk pass 15 Feb 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00032 $0.00714
Opus 5 $0.00016 $0.00357
Sonnet 5 $0.00006 $0.00143
Haiku 4.5 $0.00003 $0.00071

Measured 9d ago against content hash d275b1fdb451, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

medium-300-500ms 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 9d 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.

skills/10-by-time-scale/medium-300-500ms/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Medium Animations (300-500ms)

The 300-500ms range is standard animation territory. Long enough to be watched, short enough to not impede flow. The workhorse duration for meaningful motion.

Disney Principles at Medium Duration

All 12 Principles Applicable

Squash & Stretch: Full expression - visible deformation for bouncing, elastic elements. 15-25% stretch feels natural.

Anticipation: Clear preparation - 80-120ms anticipation before main action. Pull back before push forward.

Staging: Multi-element choreography possible - primary action leads, supporting elements follow.

Straight Ahead/Pose to Pose: Pose to pose recommended - define key positions, let easing handle in-betweens.

Follow Through: Essential - overlapping action where parts settle at different rates.

Slow In/Slow Out: Critical for naturalism - both directions need proper easing.

Arcs: Natural motion paths - elements should travel on curves matching real physics.

Secondary Action: Multiple secondary actions - hair follows head, shadow follows object.

Timing: 18-30 frames at 60fps. Enough frames for nuanced motion.

Exaggeration: Full range available - match to brand personality and context.

Solid Drawing: Complex transforms work - 3D rotations, perspective shifts.

Appeal: Character-defining animations - this is where brand personality lives.

Easing Recommendations

/* Smooth, natural motion */
transition: all 400ms cubic-bezier(0.4, 0, 0.2, 1);

/* Expressive entrance */
transition: all 450ms cubic-bezier(0.16, 1, 0.3, 1);

/* Bouncy, playful */
transition: transform 400ms cubic-bezier(0.34, 1.56, 0.64, 1);

/* Dramatic deceleration */
transition: all 350ms cubic-bezier(0, 0.55, 0.45, 1);

Best Use Cases

  • Page/view transitions
  • Complex modal sequences
  • Animated illustrations
  • Data visualization changes
  • Onboarding animations
  • Feature reveals
  • State machine transitions
  • Loading completion celebrations

Implementation Pattern

Read the full file on GitHub · 92 lines

Changes

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.

  1. 9d ago First seen · 92 lines · 32 tokens per session scan A d275b1fdb451

Subscribe to this mod's changes

medium-300-500ms is a skill published in the GitHub repository dylantarre/animation-principles (81 stars, last pushed 8mo ago), licensed MIT. It adds 32 tokens to every session and 714 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 2026-09-03.

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