Purpose: MotionSpec helps AI coding agents and frontend developers create verifiable web animations and check dynamic accessibility candidate issues in CSS already loaded on a page, such as missing prefers-reduced-motion protection and continuous animations lacking a pause path. It targets UI animations within web applications and does not generate video.
Main capabilities:
- Create animations: select primitives from the catalog, validate JSON specs, and compile to native GSAP JavaScript and CSS; meta.target accepts only vanilla-gsap.
- Check CSS dynamic effects: perform a static audit of a URL and report four categories of issues—missing effective prefers-reduced-motion protection (WCAG 2.3.3), animated properties other than transform/opacity, infinite animations with no pause path, and <marquee> or autoplaying motion exceeding 5 seconds (WCAG 2.2.2).
- Prevent regressions: use the CI example to compare results against an explicitly accepted baseline, failing the gate when a page gets worse.
Usage: the local stdio MCP exposes all five tools via npx -y motionspec, with no API key required. Hosted endpoint https://api.motionspec.dev/mcp provides keyless motion_catalog and motion_validate; hosted compilation, auditing, and statistics require a key. The repository is also a Claude Code plugin, including the /motionspec:motion and /motionspec:audit <url> skills, which you can try with claude --plugin-dir . The audit command is motion audit <url>, and --json outputs a machine-readable payload (including ok, url, status, score, findings, etc.; score is null when the page is not measurable).
Limitations: the compiler guarantees whitelisting, injection protection, reduced-motion by default, loop pause paths, and deterministic output. The audit is a static CSS scan and does not check inline style, @import, CSS-in-JS, external JS bundles, video/GIF/Canvas, flashing, or runtime JavaScript animations; a clean scan does not equal a complete accessibility or WCAG compliance assessment, nor does it constitute proof of compliance with legal frameworks such as EN 301 549 or Section 508. Audit scope is limited to 12 stylesheets, 2 MB, and 8 seconds. The MCP registry identifier is io.github.MasterPlayspots/motionspec. For more installation and guides, see https://motionspec.dev/docs。
