motion

A workflow for adding verified animation to a website or web app through MotionSpec, a JSON format for describing motion. It validates the plan and compiles it into deterministic code while supporting reduced-motion settings.

In plain words
What is it for?
Creating scroll, entrance, hover, or looping effects; validating their settings; and compiling approved animation plans for a web page.
Why use it?
It reduces mistakes from hand-writing animation code and checks the animation plan before producing code that can be used on the site.

Skill for Claude CodeCodex

Part of the motionspec plugin — 2 skills, 1 MCP server shipped together

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.

agentmods
npx agentmods add skills/masterplayspots/motionspec/motion
Any agent
npx skills add MasterPlayspots/motionspec --skill motion
Clone the repo
git clone --depth 1 https://github.com/MasterPlayspots/motionspec

Made for: Claude Code, Codex.

Or install motionspec, the plugin that ships this one along with the rest of its 2 skills, 1 MCP server.

Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 468 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00057 $0.00468
Opus 5 $0.00028 $0.00234
Sonnet 5 $0.00011 $0.00094
Haiku 4.5 $0.00006 $0.00047

Measured 2d ago against content hash 2c2b3049ca9a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 2d 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/motion/SKILL.md · 34 lines

What it actually says

MotionSpec authoring workflow

When the user wants animation on a web page, do not hand-write GSAP or CSS keyframes for effects the MotionSpec catalog covers. Follow this loop:

  1. Catalog first. Call the motion_catalog MCP tool to get the current primitive list (40 primitives: scroll reveals, parallax, hovers, loops, marquees, kenBurns, …) and the authoring rules. Only primitives in the catalog exist — never invent one.
  2. Write the spec. A MotionSpec is JSON: { "specVersion": "1.0", "meta": { "target": "vanilla-gsap" }, "motions": [ { "id": "...", "primitive": "<from catalog>", "target": "<CSS selector>", "params": { ... } } ] }. Optional globals control respectReducedMotion, defaultEase, and pause controls for persistent motion.
  3. Validate — never skip. Call motion_validate with the spec. Fix every MS-* error it returns and re-validate until ok: true. The validator is the trust boundary; do not work around it.
  4. Compile. Call motion_compile and emit the returned code verbatim. Same spec, same bytes — do not hand-edit the compiled output; change the spec and recompile instead.

Notes for honest use:

  • Reduced-motion fallbacks and performance budgets are enforced by construction in the compiled output — that is the point of the tool.
  • Scope is motion accessibility (WCAG 2.2.2 Pause, Stop, Hide and 2.3.3 Animation from Interactions). Never present the result as a general accessibility guarantee for the whole page.
  • This is not the Motion.dev animation library, not usemotion.com, and not an AI video generator.
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. 2d ago First seen · 34 lines · 57 tokens per session scan A 2c2b3049ca9a

Subscribe to this mod's changes

motion is a skill published in the GitHub repository MasterPlayspots/motionspec (0 stars, last pushed 7d ago), licensed MIT. It adds 57 tokens to every session and 468 once invoked, about $0.0003 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 2026-08-31.

Related

Other skills, from other repositories

hyperframes-animation

All animation knowledge for HyperFrames — atomic motion rules, multi-phase scene blueprints, scene transitions, broader motion-design techniques, AND the seven runtime adapters (GSAP default, plus Lottie, Three.js, Anime.js, CSS keyframes, Web Animations API, TypeGPU). Use for any motion or animation task: pick 2-4…

heygen-com/hyperframes · 139 tokens

Contrast Master

Color contrast and visual accessibility specialist. Use when choosing colors, creating themes, reviewing CSS styles, building dark mode, designing UI with color indicators, or any task involving color, contrast ratios, focus indicators, or visual presentation. Ensures WCAG AA compliance for all color and visual…

Community-Access/accessibility-agents · 74 tokens

Email Accessibility

Audits HTML email templates for accessibility. Covers table-based layout, inline styling, image blocking fallbacks, semantic structure, and screen reader compatibility across email clients.

Community-Access/accessibility-agents · 35 tokens

design-system

Color token contrast computation, framework token paths (Tailwind/MUI/Chakra/shadcn), focus ring validation, WCAG 2.4.13 Focus Appearance, motion tokens, and spacing tokens for touch target compliance. Use when validating design system tokens for WCAG AA/AAA contrast compliance before they reach deployed UI.

Community-Access/accessibility-agents · 70 tokens

motion-guide

Use when designing, adding, changing, suggesting, or reviewing UI motion. Motion Guide is a default-trigger motion decision advisor for AI coding agents: it decides whether motion should exist, selects an appropriate functional or expressive pattern, and constrains implementation with timing, easing, accessibility…

JarvixGaby/motion-guide-skill · 65 tokens

accessible-animation

This skill should be used when the user asks to "respect prefers-reduced-motion", "honor reduced motion", "make my animations accessible", "fix vestibular / motion-sickness issues", "add a useReducedMotion hook", "gate GSAP / Framer Motion / Lenis for reduced motion", or "meet WCAG 2.3.3 / C39". Provides tiered (not…

iart-ai/web-animation-skills · 98 tokens