Deprecate EnumSchema and JsonType.enumeration

mcp_examples/bin/workflow_client.dart

@@ -512,11 +512,21 @@ final class WorkflowClient extends MCPClient with RootsSupport {
           properties: properties ?? {},
           nullable: nullable,
         );
-      case JsonType.string:
+      case JsonType.string
+          when (inputSchema as StringSchema).enumValues == null:
         return gemini.Schema.string(
           description: inputSchema.description,
           nullable: nullable,
         );
+      case JsonType.string
+          when (inputSchema as StringSchema).enumValues != null:
+      case JsonType.enumeration: // ignore: deprecated_member_use
+        final schema = inputSchema as StringSchema;
+        return gemini.Schema.enumString(
+          enumValues: schema.enumValues!.toList(),
+          description: description,
+          nullable: nullable,
+        );
       case JsonType.list:
         final listSchema = inputSchema as ListSchema;
         final itemSchema =
@@ -546,13 +556,6 @@ final class WorkflowClient extends MCPClient with RootsSupport {
           description: description,
           nullable: nullable,
         );
-      case JsonType.enumeration:
-        final schema = inputSchema as EnumSchema;
-        return gemini.Schema.enumString(
-          enumValues: schema.values.toList(),
-          description: description,
-          nullable: nullable,
-        );
       default:
         throw UnimplementedError(
           'Unimplemented schema type ${inputSchema.type}',

pkgs/dart_mcp/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 0.3.2-wip
+
+- Deprecate the `EnumSchema` type in favor of the `StringSchema` with an
+  `enumValues` parameter. The `EnumSchema` type was not MCP spec compatible.
+  - Also deprecated the associated JsonType.enumeration which doesn't exist
+    in the JSON schema spec.
+
 ## 0.3.1
 
 - Fixes communication problem when a `MCPServer` is instantiated without

pkgs/dart_mcp/example/elicitations_client.dart

@@ -88,8 +88,10 @@ Do you want to accept (a), reject (r), or cancel (c) the elicitation?
       final name = property.key;
       final type = property.value.type;
       final allowedValues =
-          type == JsonType.enumeration
-              ? ' (${(property.value as EnumSchema).values.join(', ')})'
+          // ignore: deprecated_member_use_from_same_package
+          (type == JsonType.enumeration || type == JsonType.string) &&
+                  (property.value as StringSchema).enumValues != null
+              ? ' (${(property.value as StringSchema).enumValues!.join(', ')})'
               : '';
       // Ask the user in a loop until the value provided matches the schema,
       // at which point we will `break` from the loop.
@@ -99,6 +101,7 @@ Do you want to accept (a), reject (r), or cancel (c) the elicitation?
         try {
           // Convert the value to the correct type.
           final convertedValue = switch (type) {
+            // ignore: deprecated_member_use_from_same_package
             JsonType.string || JsonType.enumeration => userValue,
             JsonType.num => num.parse(userValue),
             JsonType.int => int.parse(userValue),

pkgs/dart_mcp/example/elicitations_server.dart

@@ -42,7 +42,7 @@ base class MCPServerWithElicitation extends MCPServer
           properties: {
             'name': Schema.string(),
             'age': Schema.int(),
-            'gender': Schema.enumeration(values: ['male', 'female', 'other']),
+            'gender': Schema.string(enumValues: ['male', 'female', 'other']),
           },
         ),
       ),

pkgs/dart_mcp/lib/src/api/elicitation.dart

@@ -77,7 +77,8 @@ extension type ElicitRequest._fromMap(Map<String, Object?> _value)
         case JsonType.num:
         case JsonType.int:
         case JsonType.bool:
-        case JsonType.enumeration:
+        case JsonType
+            .enumeration: // ignore: deprecated_member_use_from_same_package
           break;
         case JsonType.object:
         case JsonType.list:

pkgs/dart_mcp/lib/src/api/tools.dart

@@ -234,6 +234,7 @@ enum JsonType {
   num('number'),
   int('integer'),
   bool('boolean'),
+  @Deprecated('Use JsonType.string')
   enumeration('enum'),
   nil('null');
 
@@ -405,6 +406,7 @@ extension type Schema.fromMap(Map<String, Object?> _value) {
   static const object = ObjectSchema.new;
 
   /// Alias for [EnumSchema.new].
+  @Deprecated('Use Schema.string instead')
   static const enumeration = EnumSchema.new;
 
   /// Alias for [NullSchema.new].
@@ -480,6 +482,8 @@ extension SchemaValidation on Schema {
             accumulatedFailures,
           );
         case JsonType.string:
+        case JsonType
+            .enumeration: // ignore: deprecated_member_use_from_same_package
           isValid = (this as StringSchema)._validateString(
             data,
             currentPath,
@@ -497,12 +501,6 @@ extension SchemaValidation on Schema {
             currentPath,
             accumulatedFailures,
           );
-        case JsonType.enumeration:
-          isValid = (this as EnumSchema)._validateEnum(
-            data,
-            currentPath,
-            accumulatedFailures,
-          );
         case JsonType.bool:
           if (data is! bool) {
             isValid = false;
@@ -1077,13 +1075,15 @@ extension type const StringSchema.fromMap(Map<String, Object?> _value)
     int? minLength,
     int? maxLength,
     String? pattern,
+    Iterable<String>? enumValues,
   }) => StringSchema.fromMap({
     'type': JsonType.string.typeName,
     if (title != null) 'title': title,
     if (description != null) 'description': description,
     if (minLength != null) 'minLength': minLength,
     if (maxLength != null) 'maxLength': maxLength,
     if (pattern != null) 'pattern': pattern,
+    if (enumValues != null) 'enum': enumValues,
   });
 
   /// The minimum allowed length of this String.
@@ -1095,6 +1095,16 @@ extension type const StringSchema.fromMap(Map<String, Object?> _value)
   /// A regular expression pattern that the String must match.
   String? get pattern => _value['pattern'] as String?;
 
+  /// The allowed values for this String, corresponds to the `enum` key.
+  Iterable<String>? get enumValues {
+    final values = (_value['enum'] as Iterable?)?.cast<String>();
+    assert(
+      values?.toSet().length == values?.length,
+      "The 'enum' property has duplicate entries.",
+    );
+    return values;
+  }
+
   bool _validateString(
     Object? data,
     List<String> currentPath,
@@ -1142,13 +1152,27 @@ extension type const StringSchema.fromMap(Map<String, Object?> _value)
         ),
       );
     }
+    if (enumValues case final enumValues? when !enumValues.contains(data)) {
+      accumulatedFailures.add(
+        ValidationError(
+          ValidationErrorType.enumValueNotAllowed,
+          path: currentPath,
+          details:
+              'String "$data" is not one of the allowed values: '
+              '${enumValues.join(', ')}',
+        ),
+      );
+      return false;
+    }
     return isValid;
   }
 }
 
 /// A JSON Schema definition for a set of allowed string values.
+@Deprecated('Use StringSchema instead')
 extension type EnumSchema.fromMap(Map<String, Object?> _value)
     implements Schema {
+  @Deprecated('Use StringSchema instead')
   factory EnumSchema({
     String? title,
     String? description,
@@ -1178,36 +1202,6 @@ extension type EnumSchema.fromMap(Map<String, Object?> _value)
     );
     return values;
   }
-
-  bool _validateEnum(
-    Object? data,
-    List<String> currentPath,
-    HashSet<ValidationError> accumulatedFailures,
-  ) {
-    if (data is! String) {
-      accumulatedFailures.add(
-        ValidationError.typeMismatch(
-          path: currentPath,
-          expectedType: String,
-          actualValue: data,
-        ),
-      );
-      return false;
-    }
-    if (!values.contains(data)) {
-      accumulatedFailures.add(
-        ValidationError(
-          ValidationErrorType.enumValueNotAllowed,
-          path: currentPath,
-          details:
-              'String "$data" is not one of the allowed values: '
-              '${values.join(', ')}',
-        ),
-      );
-      return false;
-    }
-    return true;
-  }
 }
 
 /// A JSON Schema definition for a [num].

pkgs/dart_mcp/pubspec.yaml

@@ -1,5 +1,5 @@
 name: dart_mcp
-version: 0.3.1
+version: 0.3.2-wip
 description: A package for making MCP servers and clients.
 repository: https://github.com/dart-lang/ai/tree/main/pkgs/dart_mcp
 issue_tracker: https://github.com/dart-lang/ai/issues?q=is%3Aissue+is%3Aopen+label%3Apackage%3Adart_mcp

pkgs/dart_mcp/test/api/tools_test.dart

@@ -205,6 +205,7 @@ void main() {
     });
 
     test('EnumSchema', () {
+      // ignore: deprecated_member_use_from_same_package
       final schema = EnumSchema(
         title: 'Foo',
         description: 'Bar',
@@ -860,30 +861,6 @@ void main() {
       });
     });
 
-    group('Enum Specific', () {
-      test('enumValueNotAllowed', () {
-        final schema = EnumSchema(values: {'a', 'b'});
-        expectFailuresMatch(schema, 'c', [
-          ValidationError(
-            ValidationErrorType.enumValueNotAllowed,
-            path: const [],
-          ),
-        ]);
-      });
-
-      test('valid enum value', () {
-        final schema = EnumSchema(values: {'a', 'b'});
-        expectFailuresMatch(schema, 'a', []);
-      });
-
-      test('enum with non-string data', () {
-        final schema = EnumSchema(values: {'a', 'b'});
-        expectFailuresMatch(schema, 1, [
-          ValidationError(ValidationErrorType.typeMismatch, path: const []),
-        ]);
-      });
-    });
-
     group('Schema Combinators', () {
       test('allOfNotMet - one sub-schema fails', () {
         final schema = Schema.combined(
@@ -1340,6 +1317,28 @@ void main() {
           ValidationError(ValidationErrorType.patternMismatch, path: const []),
         ]);
       });
+
+      test('enumValueNotAllowed', () {
+        final schema = StringSchema(enumValues: {'a', 'b'});
+        expectFailuresMatch(schema, 'c', [
+          ValidationError(
+            ValidationErrorType.enumValueNotAllowed,
+            path: const [],
+          ),
+        ]);
+      });
+
+      test('valid enum value', () {
+        final schema = StringSchema(enumValues: {'a', 'b'});
+        expectFailuresMatch(schema, 'a', []);
+      });
+
+      test('enum with non-string data', () {
+        final schema = StringSchema(enumValues: {'a', 'b'});
+        expectFailuresMatch(schema, 1, [
+          ValidationError(ValidationErrorType.typeMismatch, path: const []),
+        ]);
+      });
     });
 
     group('Number Specific', () {

pkgs/dart_mcp_server/lib/src/mixins/dtd.dart

@@ -653,10 +653,10 @@ base mixin DartToolingDaemonSupport
           'figure out how to find the widget instead of just guessing tooltip '
           'text or other things.',
       properties: {
-        'command': Schema.enumeration(
+        'command': Schema.string(
           // Commented out values are flutter_driver commands that are not
           // supported, but may be in the future.
-          values: [
+          enumValues: [
             'get_health',
             'get_layer_tree',
             'get_render_tree',
@@ -707,13 +707,13 @@ base mixin DartToolingDaemonSupport
               'The frequency in Hz of the generated move events. '
               'Required for the scroll command',
         ),
-        'finderType': Schema.enumeration(
+        'finderType': Schema.string(
           description:
               'The kind of finder to use, if required for the command. '
               'Required for get_text, scroll, scroll_into_view, tap, waitFor, '
               'waitForAbsent, waitForTappable, get_offset, and '
               'get_diagnostics_tree',
-          values: [
+          enumValues: [
             'ByType',
             'ByValueKey',
             'ByTooltipMessage',
@@ -728,8 +728,8 @@ base mixin DartToolingDaemonSupport
           description:
               'Required for the ByValueKey finder, the String value of the key',
         ),
-        'keyValueType': Schema.enumeration(
-          values: ['int', 'String'],
+        'keyValueType': Schema.string(
+          enumValues: ['int', 'String'],
           description:
               'Required for the ByValueKey finder, the type of the key',
         ),
@@ -767,25 +767,25 @@ base mixin DartToolingDaemonSupport
           additionalProperties: true,
         ),
         // This is a boolean but uses the `true` and `false` strings.
-        'matchRoot': Schema.enumeration(
+        'matchRoot': Schema.string(
           description:
               'Required by the Descendent and Ancestor finders. '
               'Whether the widget matching `of` will be considered for a '
               'match',
-          values: ['true', 'false'],
+          enumValues: ['true', 'false'],
         ),
         // This is a boolean but uses the `true` and `false` strings.
-        'firstMatchOnly': Schema.enumeration(
+        'firstMatchOnly': Schema.string(
           description:
               'Required by the Descendent and Ancestor finders. '
               'If true then only the first ancestor or descendent matching '
               '`matching` will be returned.',
-          values: ['true', 'false'],
+          enumValues: ['true', 'false'],
         ),
-        'action': Schema.enumeration(
+        'action': Schema.string(
           description:
               'Required for send_text_input_action, the input action to send',
-          values: [
+          enumValues: [
             'none',
             'unspecified',
             'done',
@@ -806,23 +806,23 @@ base mixin DartToolingDaemonSupport
               'Maximum time in milliseconds to wait for the command to '
               'complete. Defaults to $_defaultTimeoutMs.',
         ),
-        'offsetType': Schema.enumeration(
+        'offsetType': Schema.string(
           description:
               'Offset types that can be requested by get_offset. '
               'Required for get_offset.',
-          values: [
+          enumValues: [
             'topLeft',
             'topRight',
             'bottomLeft',
             'bottomRight',
             'center',
           ],
         ),
-        'diagnosticsType': Schema.enumeration(
+        'diagnosticsType': Schema.string(
           description:
               'The type of diagnostics tree to request. '
               'Required for get_diagnostics_tree',
-          values: ['renderObject', 'widget'],
+          enumValues: ['renderObject', 'widget'],
         ),
         'subtreeDepth': Schema.int(
           description: