Failed to add MCP configuration to Claude Code

[charlesetc]

Hello! I got this error when trying to press the "Configure Claude Code" button.

Failed to add MCP configuration to Claude Code: System.MissingMemberException: Claude Code config error: Could not find project entry for parent directory '/Users/charles/code/halmi_v2/Library/PackageCache/com.gamelovers.mcp-unity' in existing config.
  at McpUnity.Utils.McpUtils.GetMcpServersConfig (Newtonsoft.Json.Linq.JObject existingConfig, System.String productName) [0x00079] in ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/Utils/McpUtils.cs:461 
  at McpUnity.Utils.McpUtils.TryMergeMcpServers (System.String configFilePath, Newtonsoft.Json.Linq.JObject mcpConfig, System.String productName) [0x0001e] in ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/Utils/McpUtils.cs:477 
  at McpUnity.Utils.McpUtils.AddToConfigFile (System.String configFilePath, System.Boolean useTabsIndentation, System.String productName) [0x00046] in ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/Utils/McpUtils.cs:198 
UnityEngine.Debug:LogError (object)
McpUnity.Utils.McpUtils:AddToConfigFile (string,bool,string) (at ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/Utils/McpUtils.cs:216)
McpUnity.Utils.McpUtils:AddToClaudeCodeConfig (bool) (at ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/Utils/McpUtils.cs:160)
McpUnity.Unity.McpUnityEditorWindow:ShowConfigButton (string,System.Func`2<bool, bool>) (at ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/UnityBridge/McpUnityEditorWindow.cs:605)
McpUnity.Unity.McpUnityEditorWindow:DrawServerTab () (at ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/UnityBridge/McpUnityEditorWindow.cs:263)
McpUnity.Unity.McpUnityEditorWindow:OnGUI () (at ./Library/PackageCache/com.gamelovers.mcp-unity/Editor/UnityBridge/McpUnityEditorWindow.cs:53)
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:219)

Thanks for any help, have a good one!

[charlesetc]

I'm not sure exactly what happened but using claude code I got it to succeed in installing with this insight:

⏺ I see the issue! The plugin is still looking for the wrong directory. Looking at the code again,
  the problem is in GetMcpServersConfig method at line 456:

  string serverPath = GetServerPath();
  string serverPathParent = Path.GetDirectoryName(serverPath)?.Replace("\\", "/");

  The GetServerPath() returns the path to the MCP server files, which is in the package cache. Then
  it gets the parent directory, which would be
  /Users/charles/code/halmi_v2/Library/PackageCache/com.gamelovers.mcp-unity, but the plugin expects
  this to be a project in your Claude Code config.

  The real issue is that the plugin should be using your actual Unity project root
  (/Users/charles/code/halmi_v2) instead of the package cache directory. Let me add the missing
  project entry that the plugin is actually looking for:

Which seems like it has the right understanding of the problem but does a weird fix?

⏺ Update(../../.claude.json)
  ⎿  Updated ../../.claude.json with 4 additions                                                  
       3410          "lastTotalCacheReadInputTokens": 255775,
       3411          "lastSessionId": "a0868b5b-3b23-430d-93c7-c7f8d7dd6372"
       3412        },
       3413 +      "/Users/charles/code/halmi_v2/Library/PackageCache/com.gamelovers.mcp-unity": {
       3414 +        "allowedTools": [],
       3415 +        "mcpServers": {}
       3416 +      },
       3417        "/Users/charles/code/halmi_v2/Halmi V2": {
       3418          "allowedTools": [],
       3419          "history": [

anyways it did successfully install.

[charlesetc]

So that did not end up working. But I was able to run this manually

claude mcp add mcp-unity node /Users/charles/code/halmi_v2/Library/PackageCache/com.gamelovers.mcp-unity/Server~/build/index.js

which added this to my ~/.claude.json

      "mcpServers": {
        "mcp-unity": {
          "type": "stdio",
          "command": "node",
          "args": [
            "/Users/charles/code/halmi_v2/Library/PackageCache/com.gamelovers.mcp-unity/Server~/build/index.js"
          ],
          "env": {}
        }
      },

and it seems to be working! Thank you for making this!

[CoderGamester]

Hello @charlesetc

Thank you for your report
Glad you found a way to solve it but it seems there is some issue in the configuration on MacOS.
To better help me solve for the other users, can you share with me your claude.json file?

• You can remove any other MCP or MCP Keys for security reasons. I just want to understand how it is searching the JSON file in your machine, as that seems to be the issue