Avatar creation for VRChat in Unity using agentic coding tools.

My blog post about it: https://sentfromspace.xyz/blog/claude-vrchat-avatar/

1. Download the .zip from this GitHub repository
2. Extract it into your Unity project root — the folder containing Assets/, Packages/, and Library/ (in Creator Companion: three dots next to the project → Open Project Folder)
3. Files land in the right places automatically — the Unity package goes into Packages/, configs go to the project root

• Claude Code (Anthropic)
• Codex (OpenAI)

Or any other capable coding agent with MCP support

Unity package (Packages/xyz.sentfromspace.agentic-tools):

• UnityMcpBridge — MCP server that lets AI agents execute C# inside the Unity Editor (read hierarchy, add components, create assets, configure settings)
• AvatarTypeChecker — post-build static analysis for avatar validation (broken animation paths, parameter mismatches, material issues)
• GestureManagerVerifier — runtime toggle verification using Gesture Manager

Agent configs:

• AGENTS.md / CLAUDE.md — detailed instructions for AI agents covering VRChat SDK, VRCFury, Poiyomi, avatar workflows, and Unity conventions
• .mcp.json — MCP server config for Claude Code
• .codex/ — MCP server config for Codex

The Unity package includes a built-in MCP server (UnityMcpBridge) that starts automatically when the Unity Editor loads — no external process or dependency needed. It listens on http://127.0.0.1:14523/mcp/ using Streamable HTTP transport and exposes a single tool: execute_csharp, which compiles and runs C# snippets on the Unity main thread with access to all loaded assemblies (Unity, VRC SDK, VRCFury, project scripts). The .mcp.json and .codex/config.toml files point Claude Code and Codex to this local server.

The agent instructions cover deep integration with:

• VRCFury — automated toggle creation, component scanning, build verification
• Poiyomi Toon Shader — material property discovery, module configuration, animated properties