Rivemcp

What rivemcp MCP server does

The rivemcp MCP server gives an AI assistant tools for creating and editing Rive animation files. It can produce runtime .riv files and editor-oriented .rev files, including animation elements such as shapes, paths, gradients, text, images, bones, meshes, keyframes, state machines, listeners, view models, data binding, layouts, and scripting scaffolding.

It also moves animation content between Rive and several other formats. Supported inputs and outputs include Lottie and dotLottie, Spline, Figma, and After Effects .aep files, with format-specific limits. After Effects files can be read and edited, but the server does not create new .aep files from scratch.

How it works

Rather than exposing every capability to the model at once, the rivemcp MCP server centers its workflow on two tools. find_tool searches for the operation that matches a task, while use_tool runs the selected operation. This reduces the tool definitions that need to be supplied to an assistant. report_problem is available for sending a problem report when the user has reviewed and agreed to submit it.

The server renders previews, GIFs, and conversion checks with Rive's GPU runtime through headless Chromium. State machines can be driven during verification, and their transitions can be read back. Conversion output includes a decision report that distinguishes content transferred cleanly from content reconstructed, dropped, or requiring a user decision. Because conversions cross format boundaries, they are inherently lossy; the server also compares rendered results with the source renderer where supported.

Setup and configuration

Claude Desktop users can install the rivemcp.mcpb release file from the latest GitHub release through Settings, Extensions, and “Install from file…”. This route does not require Node.js or a JSON configuration file.

Other MCP clients can launch the package with npx:

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

Installing the package downloads a standalone binary for the platform in use. Windows, macOS on Intel or Apple Silicon, and Linux binaries are also available from the releases page. POLYMATION_LICENSE_KEY is optional at startup; without it, the included trial allowance applies. A license key can be obtained from the Polymation website.

If a rendering operation reports that Chromium is unavailable, install it once with npx playwright install chromium.

Tools and capabilities

The rivemcp MCP server supports these workflows:

• Create Rive artwork and animation structures from scratch.
• Convert between Rive, Spline, Lottie, dotLottie, Figma, and After Effects where the format table permits it.
• Turn sprite sheets into flipbooks.
• Build a rigged character from one image.
• Generate procedural smoke, fire, or glow from a still image.
• Bake physics results into keyframes.
• Render previews and GIFs for inspection.
• Exercise state-machine transitions and read their results.

Rive, Spline, and Lottie have live authoring or conversion support as documented. Figma is a conversion source, and After Effects is an editable conversion source rather than a format that can be authored from nothing.

Limitations and notes

Conversion is not lossless, so generated files may require review. The per-decision report identifies where an asset was reconstructed, omitted, or left for the user to resolve. Rendering depends on headless Chromium being installed. The software is commercial; a trial allowance is provided, while unlimited use requires a license key.