Unity MCP Bridge

Summary

An MCP server with 120+ validated tools that lets an AI agent drive the Unity Editor directly: animator graphs, particle systems, materials, profiling, builds, and scene editing.

Problem

AI-assisted game development hits a ceiling because the AI can read a project but cannot act on it. To change a material, configure a particle system, set up an animator state machine, or run a build, the AI has to write code and ask the human to run it. The Unity MCP Bridge removes the human from that loop by exposing every Unity Editor operation as a tool the AI can call directly.

Architecture

Two-part system. A Node.js MCP server with stdio transport and Zod schema validation runs in the AI client. A Unity Editor C# package with 57+ command handlers and auto-registration runs inside Unity, connected over WebSocket. The MCP server exposes 120+ tools across animator and animation, particle systems, materials and shaders, profiler and performance, GameObject and component, asset database and prefabs, UI and transform, render pipeline, and build and test.

Outcomes

• 120+ validated tools covering every major Unity Editor surface
• 25 Animator and Animation tools (states, transitions, blend trees, sub-state machines)
• 18 Particle System tools (module-by-module config, runtime control, performance analysis)
• 11 Materials, Shaders, and Textures tools
• 9 Profiler tools with AI-generated optimization recommendations
• Orchestration tools: sequence, batch with Undo group rollback, autonomous sub-agent loop via OpenRouter

Hardest bits

• SerializedObject property access pattern for safe Unity Editor mutation with full Undo support
• Auto-registration of command handlers across all loaded assemblies for dynamic component types
• JSON-encoded parameters compatible with Unity JsonUtility plus a 12-error type taxonomy
• Atomic batch operations with Undo group rollback so multi-step edits succeed or fail together

Stack