Endpoints and resources
All endpoints are on http://127.0.0.1:<PORT>. The port is shown in Window > Unity MCP Server.
| Path | Use |
|---|---|
POST /mcp |
Streamable HTTP. Stateless; answers in JSON. Notifications get 202. Use this for Codex and other Streamable HTTP clients |
GET /sse + POST /message?sessionId=… |
Classic SSE. Each connection is its own session |
POST /message |
A JSON-RPC request and its answer, directly — handy for scripts |
GET /health |
Project name and path, process ID, package version, protocol version and transports. Answers during compilation too |
MCP protocol versions 2024-11-05 to 2025-11-25 are negotiated.
Resources
Section titled “Resources”Read-only MCP resources the AI can read at any time:
| URI | Contents |
|---|---|
unity://project/info |
Which project this server belongs to |
unity://editor/state |
Compile failures, Play / paused state, scenes being loaded and unsaved scenes |
Read unity://editor/state after a domain reload before repeating a change.
Calling a tool from a script
Section titled “Calling a tool from a script”curl -s http://127.0.0.1:<PORT>/message \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"mcp_status","arguments":{}}}'