list_resources and read_resource require explicit project_root parameter

[jrep41]

Description

The list_resources and read_resource tools require the project_root parameter to be explicitly specified, even when Unity Editor is open and connected. Without it, they only return unity://spec/script-edits.

Steps to Reproduce

1. Open Unity Editor with a project (e.g., E:\Unity_projects\con_mcp)
2. Ensure MCP is connected (verify with manage_scene action get_active - this works)
3. Call list_resources without project_root:

   {
     "pattern": "*.cs",
     "under": "Assets"
   }

4. Observe that it only returns ["unity://spec/script-edits"]

Expected Behavior

When Unity Editor is open and MCP is connected, list_resources and read_resource should automatically detect the project root from the active Unity instance.

Actual Behavior

These tools require explicit project_root parameter:

{
  "pattern": "*.cs",
  "project_root": "E:\\Unity_projects\\con_mcp",
  "under": "Assets"
}

Only then do they return the actual scripts in the project.

Environment

• OS: Windows
• Unity Version: 6.0 (6000.0.51f1)
• MCP Package: com.coplaydev.unity-mcp@030896ead96d
• Python: 3.14
• MCP Client: Claude Desktop

Additional Context

Other MCP tools like manage_scene, manage_script, and manage_gameobject work correctly without requiring project_root, which suggests the issue is specific to the resource listing/reading functionality.

The debug_request_context shows active_instance: null, which might be related to this issue.

Suggested Fix

The MCP server should automatically determine the project root from the connected Unity instance, similar to how other tools operate.