diff --git a/Sources/AnyLanguageModelMacros/GenerableMacro.swift b/Sources/AnyLanguageModelMacros/GenerableMacro.swift
index b1a008ef..a44707e7 100644
--- a/Sources/AnyLanguageModelMacros/GenerableMacro.swift
+++ b/Sources/AnyLanguageModelMacros/GenerableMacro.swift
@@ -19,6 +19,7 @@ public struct GenerableMacro: MemberMacro, ExtensionMacro {
 
             return [
                 generateRawContentProperty(),
+                generateMemberwiseInit(properties: properties),
                 generateInitFromGeneratedContent(structName: structName, properties: properties),
                 generateGeneratedContentProperty(
                     structName: structName,
@@ -69,7 +70,10 @@ public struct GenerableMacro: MemberMacro, ExtensionMacro {
         conformingTo protocols: [TypeSyntax],
         in context: some MacroExpansionContext
     ) throws -> [ExtensionDeclSyntax] {
+        let nonisolatedModifier = DeclModifierSyntax(name: .keyword(.nonisolated))
+
         let extensionDecl = ExtensionDeclSyntax(
+            modifiers: DeclModifierListSyntax([nonisolatedModifier]),
             extendedType: type,
             inheritanceClause: InheritanceClauseSyntax(
                 inheritedTypes: InheritedTypeListSyntax([
@@ -247,6 +251,91 @@ public struct GenerableMacro: MemberMacro, ExtensionMacro {
         )
     }
 
+    private static func generateMemberwiseInit(properties: [PropertyInfo]) -> DeclSyntax {
+        if properties.isEmpty {
+            return DeclSyntax(
+                stringLiteral: """
+                    nonisolated public init() {
+                        self._rawGeneratedContent = GeneratedContent(kind: .structure(properties: [:], orderedKeys: []))
+                    }
+                    """
+            )
+        }
+
+        let parameters = properties.map { prop in
+            "\(prop.name): \(prop.type)"
+        }.joined(separator: ", ")
+
+        let assignments = properties.map { prop in
+            "self.\(prop.name) = \(prop.name)"
+        }.joined(separator: "\n        ")
+
+        let propertyConversions = properties.map { prop in
+            let propName = prop.name
+            let propType = prop.type
+
+            if propType.hasSuffix("?") {
+                let baseType = String(propType.dropLast())
+                if baseType == "String" {
+                    return
+                        "properties[\"\(propName)\"] = \(propName).map { GeneratedContent($0) } ?? GeneratedContent(kind: .null)"
+                } else if baseType == "Int" || baseType == "Double" || baseType == "Float"
+                    || baseType == "Bool" || baseType == "Decimal"
+                {
+                    return
+                        "properties[\"\(propName)\"] = \(propName).map { $0.generatedContent } ?? GeneratedContent(kind: .null)"
+                } else if isDictionaryType(baseType) {
+                    return
+                        "properties[\"\(propName)\"] = \(propName).map { $0.generatedContent } ?? GeneratedContent(kind: .null)"
+                } else if baseType.hasPrefix("[") && baseType.hasSuffix("]") {
+                    return
+                        "properties[\"\(propName)\"] = \(propName).map { GeneratedContent(elements: $0) } ?? GeneratedContent(kind: .null)"
+                } else {
+                    return """
+                        if let value = \(propName) {
+                                    properties["\(propName)"] = value.generatedContent
+                                } else {
+                                    properties["\(propName)"] = GeneratedContent(kind: .null)
+                                }
+                        """
+                }
+            } else if isDictionaryType(propType) {
+                return "properties[\"\(propName)\"] = \(propName).generatedContent"
+            } else if propType.hasPrefix("[") && propType.hasSuffix("]") {
+                return "properties[\"\(propName)\"] = GeneratedContent(elements: \(propName))"
+            } else {
+                switch propType {
+                case "String":
+                    return "properties[\"\(propName)\"] = GeneratedContent(\(propName))"
+                case "Int", "Double", "Float", "Bool", "Decimal":
+                    return "properties[\"\(propName)\"] = \(propName).generatedContent"
+                default:
+                    return "properties[\"\(propName)\"] = \(propName).generatedContent"
+                }
+            }
+        }.joined(separator: "\n        ")
+
+        let orderedKeys = properties.map { "\"\($0.name)\"" }.joined(separator: ", ")
+
+        return DeclSyntax(
+            stringLiteral: """
+                nonisolated public init(\(parameters)) {
+                    \(assignments)
+                    
+                    var properties: [String: GeneratedContent] = [:]
+                    \(propertyConversions)
+                    
+                    self._rawGeneratedContent = GeneratedContent(
+                        kind: .structure(
+                            properties: properties,
+                            orderedKeys: [\(orderedKeys)]
+                        )
+                    )
+                }
+                """
+        )
+    }
+
     private static func generateInitFromGeneratedContent(
         structName: String,
         properties: [PropertyInfo]
@@ -457,16 +546,7 @@ public struct GenerableMacro: MemberMacro, ExtensionMacro {
             } else if isDictionaryType(propType) {
                 return "properties[\"\(propName)\"] = \(propName).generatedContent"
             } else if propType.hasPrefix("[") && propType.hasSuffix("]") {
-                let elementType = String(propType.dropFirst().dropLast())
-                if elementType == "String" {
-                    return "properties[\"\(propName)\"] = GeneratedContent(elements: \(propName))"
-                } else if elementType == "Int" || elementType == "Double" || elementType == "Bool"
-                    || elementType == "Float" || elementType == "Decimal"
-                {
-                    return "properties[\"\(propName)\"] = GeneratedContent(elements: \(propName))"
-                } else {
-                    return "properties[\"\(propName)\"] = GeneratedContent(elements: \(propName))"
-                }
+                return "properties[\"\(propName)\"] = GeneratedContent(elements: \(propName))"
             } else {
                 switch propType {
                 case "String":
diff --git a/Tests/AnyLanguageModelTests/GenerableMacroTests.swift b/Tests/AnyLanguageModelTests/GenerableMacroTests.swift
index 509e9425..1e6c12e7 100644
--- a/Tests/AnyLanguageModelTests/GenerableMacroTests.swift
+++ b/Tests/AnyLanguageModelTests/GenerableMacroTests.swift
@@ -25,9 +25,19 @@ private struct TestStructWithNewlines {
     var field: String
 }
 
+@Generable
+struct TestArguments {
+    @Guide(description: "A name field")
+    var name: String
+
+    @Guide(description: "An age field")
+    var age: Int
+}
+
 @Suite("Generable Macro")
 struct GenerableMacroTests {
-    @Test func multilineGuideDescription() async throws {
+    @Test("@Guide description with multiline string")
+    func multilineGuideDescription() async throws {
         let schema = TestStructWithMultilineDescription.generationSchema
         let encoder = JSONEncoder()
         let jsonData = try encoder.encode(schema)
@@ -41,7 +51,8 @@ struct GenerableMacroTests {
         #expect(decodedSchema.debugDescription.contains("object"))
     }
 
-    @Test func guideDescriptionWithSpecialCharacters() async throws {
+    @Test("@Guide description with special characters")
+    func guideDescriptionWithSpecialCharacters() async throws {
         let schema = TestStructWithSpecialCharacters.generationSchema
         let encoder = JSONEncoder()
         let jsonData = try encoder.encode(schema)
@@ -57,7 +68,8 @@ struct GenerableMacroTests {
         #expect(decodedSchema.debugDescription.contains("object"))
     }
 
-    @Test func guideDescriptionWithNewlines() async throws {
+    @Test("@Guide description with newlines")
+    func guideDescriptionWithNewlines() async throws {
         let schema = TestStructWithNewlines.generationSchema
         let encoder = JSONEncoder()
         let jsonData = try encoder.encode(schema)
@@ -78,9 +90,9 @@ struct GenerableMacroTests {
         var field: String
     }
 
-    /// Test to verify @Generable works correctly with MainActor isolation.
     @MainActor
-    @Test func mainActorIsolation() async throws {
+    @Test("@MainActor isolation")
+    func mainActorIsolation() async throws {
         let generatedContent = GeneratedContent(properties: [
             "field": "test value"
         ])
@@ -97,4 +109,30 @@ struct GenerableMacroTests {
         let partiallyGenerated = instance.asPartiallyGenerated()
         #expect(partiallyGenerated.field == "test value")
     }
+
+    @Test("Memberwise initializer")
+    func memberwiseInit() throws {
+        // This is the natural Swift way to create instances
+        let args = TestArguments(name: "Alice", age: 30)
+
+        #expect(args.name == "Alice")
+        #expect(args.age == 30)
+
+        // The generatedContent should also be properly populated
+        let content = args.generatedContent
+        #expect(content.jsonString.contains("Alice"))
+        #expect(content.jsonString.contains("30"))
+    }
+
+    @Test("Create instance from GeneratedContent")
+    func fromGeneratedContent() throws {
+        let content = GeneratedContent(properties: [
+            "name": GeneratedContent("Bob"),
+            "age": GeneratedContent(kind: .number(25)),
+        ])
+
+        let args = try TestArguments(content)
+        #expect(args.name == "Bob")
+        #expect(args.age == 25)
+    }
 }