Allow users to easily add tools in the Asset folder (#324)

* Fix issue #308: Find py files in MCPForUnityTools and version.txt

This allows for auto finding new tools. A good dir on a custom tool would look like this:
CustomTool/
├── CustomTool.MCPEnabler.asmdef
├── CustomTool.MCPEnabler.asmdef.meta
├── ExternalAssetToolFunction.cs
├── ExternalAssetToolFunction.cs.meta
├── external_asset_tool_function.py
├── external_asset_tool_function.py.meta
├── version.txt
└── version.txt.meta

CS files are left in the tools folder. The asmdef is recommended to allow for dependency on MCPForUnity when MCP For Unity is installed:

asmdef example
{
    "name": "CustomTool.MCPEnabler",
    "rootNamespace": "MCPForUnity.Editor.Tools",
    "references": [
        "CustomTool",
        "MCPForUnity.Editor"
    ],
    "includePlatforms": [
        "Editor"
    ],
    "excludePlatforms": [],
    "allowUnsafeCode": false,
    "overrideReferences": false,
    "precompiledReferences": [],
    "autoReferenced": true,
    "defineConstraints": [],
    "versionDefines": [],
    "noEngineReferences": false
}

* Follow-up: address CodeRabbit feedback for #308 (<GetToolsFolderIdentifier was duplicated>)

* Follow-up: address CodeRabbit feedback for #308 – centralize GetToolsFolderIdentifier, fix tools copy dir, and limit scan scope

* Fixing so the MCP don't removes _skipDirs e.g. __pycache__

* skip empty folders with no py files

* Rabbit: "Fix identifier collision between different package roots."

* Update MCPForUnity/Editor/Helpers/ServerInstaller.cs

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Rabbbit: Cleanup may delete server’s built-in tool subfolders — restrict to managed names.

* Fixed minor + missed onadding rabit change

* Revert "Fixed minor + missed onadding rabit change"

This reverts commit 571ca8c.

* refactor: remove Unity project tools copying and version tracking functionality

* refactor: consolidate module discovery logic into shared utility function

* Remove unused imports

* feat: add Python tool registry and sync system for MCP server integration

* feat: add auto-sync processor for Python tools with Unity editor integration

* feat: add menu item to reimport all Python files in project

Good to give users a manual option

* Fix infinite loop error

Don't react to PythonToolAsset changes - it only needs to react to Python file changes.
And we also batch asset edits to minimise the DB refreshes

* refactor: move Python tool sync menu items under Window/MCP For Unity/Tool Sync

* Update docs

* Remove duplicate header

* feat: add OnValidate handler to sync Python tools when asset is modified

This fixes the issue with deletions in the asset, now file removals are synced

* test: add unit tests for Python tools asset and sync services

* Update MCPForUnity/Editor/Helpers/PythonToolSyncProcessor.cs

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* style: remove trailing whitespace from Python tool sync files

* test: remove incomplete unit tests from ToolSyncServiceTests

* perf: optimize Python file reimport by using AssetDatabase.FindAssets instead of GetAllAssetPaths

---------

Co-authored-by: Johan Holtby <[email protected]>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: 3 people

MCPForUnity/Editor/Data/McpClients.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Runtime.InteropServices;
 using MCPForUnity.Editor.Models;
 
 namespace MCPForUnity.Editor.Data

MCPForUnity/Editor/Data/PythonToolsAsset.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+
+namespace MCPForUnity.Editor.Data
+{
+    /// <summary>
+    /// Registry of Python tool files to sync to the MCP server.
+    /// Add your Python files here - they can be stored anywhere in your project.
+    /// </summary>
+    [CreateAssetMenu(fileName = "PythonTools", menuName = "MCP For Unity/Python Tools")]
+    public class PythonToolsAsset : ScriptableObject
+    {
+        [Tooltip("Add Python files (.py) to sync to the MCP server. Files can be located anywhere in your project.")]
+        public List<TextAsset> pythonFiles = new List<TextAsset>();
+
+        [Header("Sync Options")]
+        [Tooltip("Use content hashing to detect changes (recommended). If false, always copies on startup.")]
+        public bool useContentHashing = true;
+
+        [Header("Sync State (Read-only)")]
+        [Tooltip("Internal tracking - do not modify")]
+        public List<PythonFileState> fileStates = new List<PythonFileState>();
+
+        /// <summary>
+        /// Gets all valid Python files (filters out null/missing references)
+        /// </summary>
+        public IEnumerable<TextAsset> GetValidFiles()
+        {
+            return pythonFiles.Where(f => f != null);
+        }
+
+        /// <summary>
+        /// Checks if a file needs syncing
+        /// </summary>
+        public bool NeedsSync(TextAsset file, string currentHash)
+        {
+            if (!useContentHashing) return true; // Always sync if hashing disabled
+
+            var state = fileStates.FirstOrDefault(s => s.assetGuid == GetAssetGuid(file));
+            return state == null || state.contentHash != currentHash;
+        }
+
+        /// <summary>
+        /// Records that a file was synced
+        /// </summary>
+        public void RecordSync(TextAsset file, string hash)
+        {
+            string guid = GetAssetGuid(file);
+            var state = fileStates.FirstOrDefault(s => s.assetGuid == guid);
+
+            if (state == null)
+            {
+                state = new PythonFileState { assetGuid = guid };
+                fileStates.Add(state);
+            }
+
+            state.contentHash = hash;
+            state.lastSyncTime = DateTime.UtcNow;
+            state.fileName = file.name;
+        }
+
+        /// <summary>
+        /// Removes state entries for files no longer in the list
+        /// </summary>
+        public void CleanupStaleStates()
+        {
+            var validGuids = new HashSet<string>(GetValidFiles().Select(GetAssetGuid));
+            fileStates.RemoveAll(s => !validGuids.Contains(s.assetGuid));
+        }
+
+        private string GetAssetGuid(TextAsset asset)
+        {
+            return UnityEditor.AssetDatabase.AssetPathToGUID(UnityEditor.AssetDatabase.GetAssetPath(asset));
+        }
+
+        /// <summary>
+        /// Called when the asset is modified in the Inspector
+        /// Triggers sync to handle file additions/removals
+        /// </summary>
+        private void OnValidate()
+        {
+            // Cleanup stale states immediately
+            CleanupStaleStates();
+            
+            // Trigger sync after a delay to handle file removals
+            // Delay ensures the asset is saved before sync runs
+            UnityEditor.EditorApplication.delayCall += () =>
+            {
+                if (this != null) // Check if asset still exists
+                {
+                    MCPForUnity.Editor.Helpers.PythonToolSyncProcessor.SyncAllTools();
+                }
+            };
+        }
+    }
+
+    [Serializable]
+    public class PythonFileState
+    {
+        public string assetGuid;
+        public string fileName;
+        public string contentHash;
+        public DateTime lastSyncTime;
+    }
+}

MCPForUnity/Editor/Data/PythonToolsAsset.cs.meta

@@ -0,0 +1,192 @@
+using System.IO;
+using System.Linq;
+using MCPForUnity.Editor.Data;
+using MCPForUnity.Editor.Services;
+using UnityEditor;
+using UnityEngine;
+
+namespace MCPForUnity.Editor.Helpers
+{
+    /// <summary>
+    /// Automatically syncs Python tools to the MCP server when:
+    /// - PythonToolsAsset is modified
+    /// - Python files are imported/reimported
+    /// - Unity starts up
+    /// </summary>
+    [InitializeOnLoad]
+    public class PythonToolSyncProcessor : AssetPostprocessor
+    {
+        private const string SyncEnabledKey = "MCPForUnity.AutoSyncEnabled";
+        private static bool _isSyncing = false;
+
+        static PythonToolSyncProcessor()
+        {
+            // Sync on Unity startup
+            EditorApplication.delayCall += () =>
+            {
+                if (IsAutoSyncEnabled())
+                {
+                    SyncAllTools();
+                }
+            };
+        }
+
+        /// <summary>
+        /// Called after any assets are imported, deleted, or moved
+        /// </summary>
+        private static void OnPostprocessAllAssets(
+            string[] importedAssets,
+            string[] deletedAssets,
+            string[] movedAssets,
+            string[] movedFromAssetPaths)
+        {
+            // Prevent infinite loop - don't process if we're currently syncing
+            if (_isSyncing || !IsAutoSyncEnabled())
+                return;
+
+            bool needsSync = false;
+
+            // Only check for .py file changes, not PythonToolsAsset changes
+            // (PythonToolsAsset changes are internal state updates from syncing)
+            foreach (string path in importedAssets.Concat(movedAssets))
+            {
+                // Check if any .py files were modified
+                if (path.EndsWith(".py"))
+                {
+                    needsSync = true;
+                    break;
+                }
+            }
+
+            // Check if any .py files were deleted
+            if (!needsSync && deletedAssets.Any(path => path.EndsWith(".py")))
+            {
+                needsSync = true;
+            }
+
+            if (needsSync)
+            {
+                SyncAllTools();
+            }
+        }
+
+        /// <summary>
+        /// Syncs all Python tools from all PythonToolsAsset instances to the MCP server
+        /// </summary>
+        public static void SyncAllTools()
+        {
+            // Prevent re-entrant calls
+            if (_isSyncing)
+            {
+                McpLog.Warn("Sync already in progress, skipping...");
+                return;
+            }
+
+            _isSyncing = true;
+            try
+            {
+                if (!ServerPathResolver.TryFindEmbeddedServerSource(out string srcPath))
+                {
+                    McpLog.Warn("Cannot sync Python tools: MCP server source not found");
+                    return;
+                }
+
+                string toolsDir = Path.Combine(srcPath, "tools", "custom");
+
+                var result = MCPServiceLocator.ToolSync.SyncProjectTools(toolsDir);
+
+                if (result.Success)
+                {
+                    if (result.CopiedCount > 0 || result.SkippedCount > 0)
+                    {
+                        McpLog.Info($"Python tools synced: {result.CopiedCount} copied, {result.SkippedCount} skipped");
+                    }
+                }
+                else
+                {
+                    McpLog.Error($"Python tool sync failed with {result.ErrorCount} errors");
+                    foreach (var msg in result.Messages)
+                    {
+                        McpLog.Error($"  - {msg}");
+                    }
+                }
+            }
+            catch (System.Exception ex)
+            {
+                McpLog.Error($"Python tool sync exception: {ex.Message}");
+            }
+            finally
+            {
+                _isSyncing = false;
+            }
+        }
+
+        /// <summary>
+        /// Checks if auto-sync is enabled (default: true)
+        /// </summary>
+        public static bool IsAutoSyncEnabled()
+        {
+            return EditorPrefs.GetBool(SyncEnabledKey, true);
+        }
+
+        /// <summary>
+        /// Enables or disables auto-sync
+        /// </summary>
+        public static void SetAutoSyncEnabled(bool enabled)
+        {
+            EditorPrefs.SetBool(SyncEnabledKey, enabled);
+            McpLog.Info($"Python tool auto-sync {(enabled ? "enabled" : "disabled")}");
+        }
+
+        /// <summary>
+        /// Menu item to reimport all Python files in the project
+        /// </summary>
+        [MenuItem("Window/MCP For Unity/Tool Sync/Reimport Python Files", priority = 99)]
+        public static void ReimportPythonFiles()
+        {
+            // Find all Python files (imported as TextAssets by PythonFileImporter)
+            var pythonGuids = AssetDatabase.FindAssets("t:TextAsset", new[] { "Assets" })
+                .Select(AssetDatabase.GUIDToAssetPath)
+                .Where(path => path.EndsWith(".py", System.StringComparison.OrdinalIgnoreCase))
+                .ToArray();
+
+            foreach (string path in pythonGuids)
+            {
+                AssetDatabase.ImportAsset(path, ImportAssetOptions.ForceUpdate);
+            }
+
+            int count = pythonGuids.Length;
+            McpLog.Info($"Reimported {count} Python files");
+            AssetDatabase.Refresh();
+        }
+
+        /// <summary>
+        /// Menu item to manually trigger sync
+        /// </summary>
+        [MenuItem("Window/MCP For Unity/Tool Sync/Sync Python Tools", priority = 100)]
+        public static void ManualSync()
+        {
+            McpLog.Info("Manually syncing Python tools...");
+            SyncAllTools();
+        }
+
+        /// <summary>
+        /// Menu item to toggle auto-sync
+        /// </summary>
+        [MenuItem("Window/MCP For Unity/Tool Sync/Auto-Sync Python Tools", priority = 101)]
+        public static void ToggleAutoSync()
+        {
+            SetAutoSyncEnabled(!IsAutoSyncEnabled());
+        }
+
+        /// <summary>
+        /// Validate menu item (shows checkmark when enabled)
+        /// </summary>
+        [MenuItem("Window/MCP For Unity/Tool Sync/Auto-Sync Python Tools", true, priority = 101)]
+        public static bool ToggleAutoSyncValidate()
+        {
+            Menu.SetChecked("Window/MCP For Unity/Tool Sync/Auto-Sync Python Tools", IsAutoSyncEnabled());
+            return true;
+        }
+    }
+}

MCPForUnity/Editor/Helpers/PythonToolSyncProcessor.cs

@@ -65,6 +65,7 @@ public static void EnsureServerInstalled()
                     // Copy the entire UnityMcpServer folder (parent of src)
                     string embeddedRoot = Path.GetDirectoryName(embeddedSrc) ?? embeddedSrc; // go up from src to UnityMcpServer
                     CopyDirectoryRecursive(embeddedRoot, destRoot);
+
                     // Write/refresh version file
                     try { File.WriteAllText(Path.Combine(destSrc, VersionFileName), embeddedVer ?? "unknown"); } catch { }
                     McpLog.Info($"Installed/updated server to {destRoot} (version {embeddedVer}).");
@@ -410,6 +411,7 @@ private static bool TryGetEmbeddedServerSource(out string srcPath)
         }
 
         private static readonly string[] _skipDirs = { ".venv", "__pycache__", ".pytest_cache", ".mypy_cache", ".git" };
+
         private static void CopyDirectoryRecursive(string sourceDir, string destinationDir)
         {
             Directory.CreateDirectory(destinationDir);

MCPForUnity/Editor/Helpers/PythonToolSyncProcessor.cs.meta

@@ -0,0 +1,21 @@
+using UnityEngine;
+using UnityEditor.AssetImporters;
+using System.IO;
+
+namespace MCPForUnity.Editor.Importers
+{
+    /// <summary>
+    /// Custom importer that allows Unity to recognize .py files as TextAssets.
+    /// This enables Python files to be selected in the Inspector and used like any other text asset.
+    /// </summary>
+    [ScriptedImporter(1, "py")]
+    public class PythonFileImporter : ScriptedImporter
+    {
+        public override void OnImportAsset(AssetImportContext ctx)
+        {
+            var textAsset = new TextAsset(File.ReadAllText(ctx.assetPath));
+            ctx.AddObjectToAsset("main obj", textAsset);
+            ctx.SetMainObject(textAsset);
+        }
+    }
+}