VRM Toolkit

An MCP (Model Context Protocol) server that lets an AI agent inspect, validate and preview VRM / VRMA files on your machine. Five tools, stdio transport, no network access at runtime.

VRM / VRMAファイルの検品・情報抽出・プレビューをAIエージェントから使えるようにする MCPサーバーです。ツールは5本、stdioトランスポート、実行時のネットワークアクセスなし。

Structural tools (vrm_inspect,vrm_validate,vrma_inspect) parse the GLB/glTF container directly in Node and need no browser. Rendering tools (vrma_preview,vrm_snapshot) use an already-installed Chromium-based browser viapuppeteer-core; nothing is downloaded.

構造系3ツールはNode単体でGLB/glTFを直接パースし、ブラウザ不要。描画系2ツールは インストール済みのChromium系ブラウザをpuppeteer-coreで使います(追加ダウンロードなし)。

Supported inputs: VRM 0.x (extensions.VRM), VRM 1.0 (extensions.VRMC_vrm), VRMA (extensions.VRMC_vrm_animation), GLB container or plain glTF JSON.

- Node.js 20+
- Forvrma_preview/vrm_snapshot: a local Chrome or Edge (auto-detected; override with theVRM_TOOLKIT_CHROMEenvironment variable)
- Input size budget: 512 MiB by default (VRM_TOOLKIT_MAX_BYTESto override)

Register with Claude Code / Claude Codeへの登録:

claude mcp add vrm-toolkit -- npx -y vrm-toolkit-mcp

Other MCP hosts / その他のMCPホスト: commandnpx, args["-y", "vrm-toolkit-mcp"](stdio).

npm install npm run build claude mcp add vrm-toolkit -- node /absolute/path/to/vrm-toolkit/dist/main.js

Real outputs from the local test run (2026-08-05, file paths shortened). ローカルテスト実行(2026-08-05)の実出力です(パスは短縮表記)。

Input: a VRoid Studio-exported VRM 1.0 avatar (15.7 MB).

{ "file": { "path": "...\\V1.vrm", "bytes": 15737992, "container": "glb" }, "vrm": { "specFamily": "vrm1", "specVersion": "1.0" }, "meta": { "name": "V1", "authors": ["D"], "licenseUrl": "https://vrm.dev/licenses/1.0/", "avatarPermission": "onlyAuthor", "commercialUsage": "corporation", "creditNotation": "required", "allowRedistribution": false, "modification": "prohibited" }, "humanoid": { "mappedBoneCount": 54, "bones": [ { "bone": "hips", "node": 1, "nodeName": "J_Bip_C_Hips" }, { "bone": "spine", "node": 34, "nodeName": "J_Bip_C_Spine" } ], "missingRequiredBones": [] }, "expressions": { "presetCount": 14, "presets": ["happy", "angry", "sad", "..."] }, "geometry": { "meshCount": 3, "totalVertices": 103489, "totalTriangles": 33484, "perMesh": [ { "name": "Face (merged)", "vertices": 33640, "triangles": 7308 }, { "name": "Body (merged)", "vertices": 57128, "triangles": 11548 }, { "name": "Hair001 (merged)", "vertices": 12721, "triangles": 14628 } ] }, "textures": { "imageCount": 26, "totalImageBytes": 8033934, "maxDimension": 2048 }, "materials": { "materialCount": 17 } }

(Output truncated for readability; the tool returns the full bone and image lists.)

{ "file": { "path": "...\\motion-walk-forward.vrma", "bytes": 3268, "container": "glb" }, "vrma": { "specVersion": "1.0" }, "humanoid": { "mappedBoneCount": 16, "bones": ["hips", "spine", "chest", "head", "..."] }, "animation": { "animationCount": 1, "channelCount": 2, "channelsByPath": { "translation": 1, "rotation": 1, "scale": 0, "weights": 0 }, "totalKeyframes": 62, "durationSec": 1.25, "fpsEstimate": 24, "frameCountEstimate": 31, "humanoidBoneTracks": [ { "bone": "hips", "paths": ["translation"] }, { "bone": "chest", "paths": ["rotation"] } ] } }

A finding list with stable codes and severities:

{ "ok": false, "errorCount": 1, "warningCount": 1, "findings": [ { "severity": "error", "code": "HUMANOID_REQUIRED_BONE_MISSING", "message": "required humanoid bone is not mapped: leftHand (vrm1 required set)" }, { "severity": "warning", "code": "META_LICENSE_OTHER_URL_MISSING", "message": "licenseName is Other but otherLicenseUrl is empty" } ] }

{ "output_path": "...\\v1-three-quarter-snapshot.png", "format": "png", "bytes": 194005, "width": 768, "height": 1024, "view": "three_quarter", "pose": "rest", "humanoid_bone_count": 54 }

{ "output_path": "...\\v1-walk-preview.webm", "format": "webm", "bytes": 313597, "width": 768, "height": 768, "clip_duration_sec": 1.25, "recorded_duration_sec": 3, "fps": 30 }

Every failure is a structured tool error with one of:FILE_NOT_FOUND,SIZE_BUDGET_EXCEEDED,NOT_A_GLB,NOT_A_VRM,NOT_A_VRMA,BROWSER_NOT_FOUND,RENDER_FAILED,OUTPUT_WRITE_FAILED. The server process never crashes on a bad input file.

All processing is local. The server opens no network connection, sends no telemetry, and writes only the output files you name. / 処理はすべてローカルです。ネットワーク接続・テレメトリ送信は なく、書き込みは指定した出力ファイルのみです。

npm test # build + 25 self-verification tests (structural, boundary, headless rendering)

Rendering tests skip with a notice when no local Chrome/Edge is found.

MIT (seeLICENSE). / MITライセンス(LICENSE参照)。

MCP bridge between an AI agent and a live Aseprite session, same machine or agent-in-a-VM