Polymation

Polymation (rivemcp)

An MCP server that authors Rive files and converts other animation formats into them — offline, with no design app and no account. Your AI assistant describes the animation; Polymation writes the file, renders it with Rive's own runtime to check it, and reports every decision a conversion had to make.

• Rive, from scratch — runtime .riv and editor .rev (opens in the Rive editor), covering the whole runtime: shapes, paths, gradients, feathering, text, images, bones and meshes, keyframes, state machines, listeners, view models and data binding, layouts, scripting scaffolding.
• Conversion into Rive — Lottie / dotLottie, After Effects .aep (read directly, no After Effects needed), Adobe Animate .fla, Figma (including Figma Motion timelines), Spline and glTF, plus Rive back out to Lottie, dotLottie, Spline and Figma. Every conversion comes with a per-decision report — clean, reconstructed, dropped, or needs your call — and a rendered comparison against the source's own renderer.
• Verified, not assumed — previews, GIFs and conversion checks render headlessly with Rive's GPU runtime; state machines can be driven and their transitions read back.
• AI art into animation — a clip from your own video model becomes a looping flipbook and a sprite sheet a game engine reads; a picture or layered PSD becomes a rigged character; walk frames become one rig with bone keyframes; a still gets procedural smoke, fire or glow.
• Pixel art — an image model's "pixel art" snapped onto a real grid; pixel characters rigged and animated from a library (idle, walk, run, wave, sit…) with outfits, expressions and body types, baked for every Rive runtime or posed and dressed live; always drawn crisp.
• Art over a layout — block a scene out with shapes and animate it; your own image model paints it, and the painting goes back onto the same objects with the animation and interactions kept. In 3D, models from your image-to-3D generator are placed where the layout had each thing.
• Agent skills, one per job — npx skills add paradoxsyn/rivemcp-releases offers eight: polymation (everything), lottie-to-rive, fix-ai-pixel-art, video-to-sprite-sheet, pixel-character-animation, rive-state-machines, rig-character-from-image and greybox-to-art. Add --skill for one.

226 MCP tools, reached through two: find_tool finds the one for a job and use_tool runs it, so an assistant carries about 2,400 tokens of tool definitions per message instead of 50,000+. A third, report_problem, sends the team a problem report — only one you have seen and agreed to send.

Format support

Every conversion crosses a model boundary, so every one is lossy — the report says what came across clean, what was reconstructed, what was dropped and what needs your call. After Effects is read natively (no After Effects install, no plugin) and can be edited and saved back; writing a .aep from scratch is not offered, because without After Effects there is no way to check such a file would open.

Quick Start

Claude Desktop — one click

1. Download `rivemcp.mcpb` from the latest release.
2. Claude Desktop → Settings → Extensions → Install from file… and pick it. No Node.js, no JSON.

Claude Code — as a plugin

/plugin marketplace add paradoxsyn/rivemcp-releases

/plugin install polymation@polymation

The plugin adds the server and the eight skills together, and asks for a licence key you can leave empty. It needs Node.js 18 or newer.

Any MCP client (Claude Code, Cursor, Windsurf, VS Code…)

{

"mcpServers": { "polymation": { "command": "npx", "args": ["-y", "rivemcp"], "env": { "POLYMATION_LICENSE_KEY": "your-key" } } } }

Installing the package downloads the standalone binary for your platform. The licence key is optional to start: without one, the trial allowance applies. Keys are at polymation.stunning.gg.

Standalone binaries

Windows, macOS (Intel and Apple Silicon) and Linux builds — no Node.js needed — are on the releases page.

Rendering

Previews, GIFs and conversion checks render with Rive's own runtime in a headless Chromium. If a render tool reports that Chromium is missing, run npx playwright install chromium once.

Usage counts

Polymation sends counts of which of its tools ran and whether they worked, with its version and how it was installed. Nothing about you: no identifier of any kind, and never your files, paths, tool settings, prompts or error messages. Details: privacy notice.

With a paid licence key it also sends that key's activity record: per day and tool, how many calls worked and wrote a finished file, with the key and device identifier, kept 540 days to answer billing questions and payment disputes (details). A free trial sends none.

What the plugin runs, fetches and sends

The plugin holds no program of its own: a manifest, an icon and the skills (Markdown). Enabled, it starts one local MCP server and nothing else — no hooks, no commands, no background process.

• Runs: npx -y rivemcp@ , the published npm package pinned to the plugin's own version. The package is a small launcher; installing it downloads the Polymation program for your platform (Windows, macOS, Linux) from this repository's release of the same version on github.com, and the launcher runs that program. The program is a closed, compiled build.
• Reads and writes: only the files you ask it for, on your own computer. Previews are drawn in a headless Chromium (Playwright's, or Chrome or Edge if installed). No file, path, prompt or tool setting is sent anywhere.
• Sends, to `api-rivemcp.stunning.gg` only: a licence check (your key if you set one, and a device identifier); the count of free exports used by this device when no key is set; counts of which tools ran and whether they worked, with the version and how it was installed, and no identifier; with a paid key, that key's per-day tool counts; and a problem report only when you have read it and agreed to send it.

Privacy Policy

polymation.stunning.gg/privacy says what is collected, why, for how long, and how to ask for it or have it removed.

Licence

Commercial software — see LICENSE. A trial allowance is included; a key from polymation.stunning.gg unlocks unlimited use.