Require roots for all CLI tools

pkgs/dart_tooling_mcp_server/lib/src/mixins/analyzer.dart

@@ -271,7 +271,7 @@ base mixin DartAnalyzerSupport
     return CallToolResult(content: [TextContent(text: jsonEncode(result))]);
   }
 
-  /// Ensures that all prerequites for any analysis task are met.
+  /// Ensures that all prerequisites for any analysis task are met.
   ///
   /// Returns an error response if any prerequisite is not met, otherwise
   /// returns `null`.

pkgs/dart_tooling_mcp_server/lib/src/mixins/dart_cli.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:dart_mcp/server.dart';
 
 import '../utils/cli_utils.dart';
+import '../utils/constants.dart';
 import '../utils/process_manager.dart';
 
 // TODO: migrate the analyze files tool to use this mixin and run the
@@ -17,13 +18,19 @@ import '../utils/process_manager.dart';
 ///
 /// The MCPServer must already have the [ToolsSupport] and [LoggingSupport]
 /// mixins applied.
-base mixin DartCliSupport on ToolsSupport, LoggingSupport
+base mixin DartCliSupport on ToolsSupport, LoggingSupport, RootsTrackingSupport
     implements ProcessManagerSupport {
   @override
   FutureOr<InitializeResult> initialize(InitializeRequest request) {
-    registerTool(dartFixTool, _runDartFixTool);
-    registerTool(dartFormatTool, _runDartFormatTool);
-    return super.initialize(request);
+    try {
+      return super.initialize(request);
+    } finally {
+      // Can't call this until after `super.initialize`.
+      if (supportsRoots) {
+        registerTool(dartFixTool, _runDartFixTool);
+        registerTool(dartFormatTool, _runDartFormatTool);
+      }
+    }
   }
 
   /// Implementation of the [dartFixTool].
@@ -33,6 +40,7 @@ base mixin DartCliSupport on ToolsSupport, LoggingSupport
       command: ['dart', 'fix', '--apply'],
       commandDescription: 'dart fix',
       processManager: processManager,
+      knownRoots: await roots,
     );
   }
 
@@ -44,6 +52,7 @@ base mixin DartCliSupport on ToolsSupport, LoggingSupport
       commandDescription: 'dart format',
       processManager: processManager,
       defaultPaths: ['.'],
+      knownRoots: await roots,
     );
   }
 
@@ -52,22 +61,7 @@ base mixin DartCliSupport on ToolsSupport, LoggingSupport
     description: 'Runs `dart fix --apply` for the given project roots.',
     annotations: ToolAnnotations(title: 'Dart fix', destructiveHint: true),
     inputSchema: Schema.object(
-      properties: {
-        'roots': Schema.list(
-          title: 'All projects roots to run dart fix in.',
-          description:
-              'These must match a root returned by a call to "listRoots".',
-          items: Schema.object(
-            properties: {
-              'root': Schema.string(
-                title: 'The URI of the project root to run `dart fix` in.',
-              ),
-            },
-            required: ['root'],
-          ),
-        ),
-      },
-      required: ['roots'],
+      properties: {ParameterNames.roots: rootsSchema()},
     ),
   );
 
@@ -76,29 +70,7 @@ base mixin DartCliSupport on ToolsSupport, LoggingSupport
     description: 'Runs `dart format .` for the given project roots.',
     annotations: ToolAnnotations(title: 'Dart format', destructiveHint: true),
     inputSchema: Schema.object(
-      properties: {
-        'roots': Schema.list(
-          title: 'All projects roots to run dart format in.',
-          description:
-              'These must match a root returned by a call to "listRoots".',
-          items: Schema.object(
-            properties: {
-              'root': Schema.string(
-                title: 'The URI of the project root to run `dart format` in.',
-              ),
-              'paths': Schema.list(
-                title:
-                    'Relative or absolute paths to analyze under the '
-                    '"root". Paths must correspond to files and not '
-                    'directories.',
-                items: Schema.string(),
-              ),
-            },
-            required: ['root'],
-          ),
-        ),
-      },
-      required: ['roots'],
+      properties: {ParameterNames.roots: rootsSchema(supportsPaths: true)},
     ),
   );
 }

pkgs/dart_tooling_mcp_server/lib/src/mixins/pub.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:dart_mcp/server.dart';
 
 import '../utils/cli_utils.dart';
+import '../utils/constants.dart';
 import '../utils/process_manager.dart';
 
 /// Mix this in to any MCPServer to add support for running Pub commands like
@@ -16,17 +17,22 @@ import '../utils/process_manager.dart';
 ///
 /// The MCPServer must already have the [ToolsSupport] and [LoggingSupport]
 /// mixins applied.
-base mixin PubSupport on ToolsSupport, LoggingSupport
+base mixin PubSupport on ToolsSupport, LoggingSupport, RootsTrackingSupport
     implements ProcessManagerSupport {
   @override
   FutureOr<InitializeResult> initialize(InitializeRequest request) {
-    registerTool(pubTool, _runDartPubTool);
-    return super.initialize(request);
+    try {
+      return super.initialize(request);
+    } finally {
+      if (supportsRoots) {
+        registerTool(pubTool, _runDartPubTool);
+      }
+    }
   }
 
   /// Implementation of the [pubTool].
   Future<CallToolResult> _runDartPubTool(CallToolRequest request) async {
-    final command = request.arguments?['command'] as String?;
+    final command = request.arguments?[ParameterNames.command] as String?;
     if (command == null) {
       return CallToolResult(
         content: [TextContent(text: 'Missing required argument `command`.')],
@@ -48,7 +54,8 @@ base mixin PubSupport on ToolsSupport, LoggingSupport
       );
     }
 
-    final packageName = request.arguments?['packageName'] as String?;
+    final packageName =
+        request.arguments?[ParameterNames.packageName] as String?;
     if (matchingCommand.requiresPackageName && packageName == null) {
       return CallToolResult(
         content: [
@@ -69,6 +76,7 @@ base mixin PubSupport on ToolsSupport, LoggingSupport
       command: ['dart', 'pub', command, if (packageName != null) packageName],
       commandDescription: 'dart pub $command',
       processManager: processManager,
+      knownRoots: await roots,
     );
   }
 
@@ -80,34 +88,20 @@ base mixin PubSupport on ToolsSupport, LoggingSupport
     annotations: ToolAnnotations(title: 'pub', readOnlyHint: false),
     inputSchema: Schema.object(
       properties: {
-        'command': Schema.string(
+        ParameterNames.command: Schema.string(
           title: 'The dart pub command to run.',
           description:
               'Currently only ${SupportedPubCommand.listAll} are supported.',
         ),
-        'packageName': Schema.string(
+        ParameterNames.packageName: Schema.string(
           title: 'The package name to run the command for.',
           description:
               'This is required for the '
               '${SupportedPubCommand.listAllThatRequirePackageName} commands.',
         ),
-        'roots': Schema.list(
-          title: 'All projects roots to run the dart pub command in.',
-          description:
-              'These must match a root returned by a call to "listRoots".',
-          items: Schema.object(
-            properties: {
-              'root': Schema.string(
-                title:
-                    'The URI of the project root to run the dart pub command '
-                    'in.',
-              ),
-            },
-            required: ['root'],
-          ),
-        ),
+        ParameterNames.roots: rootsSchema(),
       },
-      required: ['command', 'roots'],
+      required: [ParameterNames.command],
     ),
   );
 }

pkgs/dart_tooling_mcp_server/lib/src/utils/cli_utils.dart

@@ -5,8 +5,11 @@
 import 'dart:io';
 
 import 'package:dart_mcp/server.dart';
+import 'package:path/path.dart' as p;
 import 'package:process/process.dart';
 
+import 'constants.dart';
+
 /// Runs [command] in each of the project roots specified in the [request].
 ///
 /// The [command] should be a list of strings that can be passed directly to
@@ -16,6 +19,10 @@ import 'package:process/process.dart';
 /// being run. For example, if the command is `['dart', 'fix', '--apply']`, the
 /// command description might be `dart fix`.
 ///
+/// The [knownRoots] are used by default if no roots are provided as an
+/// argument on the [request]. Otherwise, all roots provided in the request
+/// arguments must still be encapsulated by the [knownRoots].
+///
 /// [defaultPaths] may be specified if one or more path arguments are required
 /// for the command (e.g. `dart format <default paths>`). The paths can be
 /// absolute or relative paths that point to the directories on which the
@@ -29,20 +36,23 @@ Future<CallToolResult> runCommandInRoots(
   required List<String> command,
   required String commandDescription,
   required ProcessManager processManager,
+  required List<Root> knownRoots,
   List<String> defaultPaths = const <String>[],
 }) async {
-  final rootConfigs =
-      (request.arguments?['roots'] as List?)?.cast<Map<String, Object?>>();
-  if (rootConfigs == null) {
-    return CallToolResult(
-      content: [TextContent(text: 'Missing required argument `roots`.')],
-      isError: true,
-    );
+  var rootConfigs =
+      (request.arguments?[ParameterNames.roots] as List?)
+          ?.cast<Map<String, Object?>>();
+
+  // Default to use the known roots if none were specified.
+  if (rootConfigs == null || rootConfigs.isEmpty) {
+    rootConfigs = [
+      for (final root in knownRoots) {ParameterNames.root: root.uri},
+    ];
   }
 
   final outputs = <TextContent>[];
   for (var rootConfig in rootConfigs) {
-    final rootUriString = rootConfig['root'] as String?;
+    final rootUriString = rootConfig[ParameterNames.root] as String?;
     if (rootUriString == null) {
       // This shouldn't happen based on the schema, but handle defensively.
       return CallToolResult(
@@ -53,6 +63,19 @@ Future<CallToolResult> runCommandInRoots(
       );
     }
 
+    if (!_isAllowedRoot(rootUriString, knownRoots)) {
+      return CallToolResult(
+        content: [
+          TextContent(
+            text:
+                'Invalid root $rootUriString, must be under one of the '
+                'registered project roots:\n\n${knownRoots.join('\n')}',
+          ),
+        ],
+        isError: true,
+      );
+    }
+
     final rootUri = Uri.parse(rootUriString);
     if (rootUri.scheme != 'file') {
       return CallToolResult(
@@ -68,9 +91,28 @@ Future<CallToolResult> runCommandInRoots(
     }
     final projectRoot = Directory(rootUri.toFilePath());
 
-    final commandWithPaths = List<String>.from(command);
-    final paths = (rootConfig['paths'] as List?)?.cast<String>();
-    commandWithPaths.addAll(paths ?? defaultPaths);
+    final commandWithPaths = List.of(command);
+    final paths =
+        (rootConfig[ParameterNames.paths] as List?)?.cast<String>() ??
+        defaultPaths;
+    final invalidPaths = paths.where((path) {
+      final resolvedPath = rootUri.resolve(path).toString();
+      return rootUriString != resolvedPath &&
+          !p.isWithin(rootUriString, resolvedPath);
+    });
+    if (invalidPaths.isNotEmpty) {
+      return CallToolResult(
+        content: [
+          TextContent(
+            text:
+                'Paths are not allowed to escape their project root:\n'
+                '${invalidPaths.join('\n')}',
+          ),
+        ],
+        isError: true,
+      );
+    }
+    commandWithPaths.addAll(paths);
 
     final result = await processManager.run(
       commandWithPaths,
@@ -102,3 +144,35 @@ Future<CallToolResult> runCommandInRoots(
   }
   return CallToolResult(content: outputs);
 }
+
+/// Returns whether or not [rootUri] is an allowed root, either exactly matching
+/// or under on of the [knownRoots].
+bool _isAllowedRoot(String rootUri, List<Root> knownRoots) =>
+    knownRoots.any((knownRoot) {
+      final knownRootUri = Uri.parse(knownRoot.uri);
+      final resolvedRoot = knownRootUri.resolve(rootUri).toString();
+      return knownRoot.uri == resolvedRoot ||
+          p.isWithin(knownRoot.uri, resolvedRoot);
+    });
+
+/// The schema for the `roots` parameter for any tool that accepts it.
+ListSchema rootsSchema({bool supportsPaths = false}) => Schema.list(
+  title: 'All projects roots to run this tool in.',
+  items: Schema.object(
+    properties: {
+      ParameterNames.root: Schema.string(
+        title: 'The URI of the project root to run this tool in.',
+        description:
+            'This must be equal to or a subdirectory of one of the roots '
+            'returned by a call to "listRoots".',
+      ),
+      if (supportsPaths)
+        ParameterNames.paths: Schema.list(
+          title:
+              'Paths to run this tool on. Must resolve to a path that is '
+              'within the "root".',
+        ),
+    },
+    required: [ParameterNames.root],
+  ),
+);

pkgs/dart_tooling_mcp_server/lib/src/utils/constants.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// A namespace for all the parameter names.
+extension ParameterNames on Never {
+  static const command = 'command';
+  static const packageName = 'packageName';
+  static const paths = 'paths';
+  static const root = 'root';
+  static const roots = 'roots';
+}