diff --git a/lib/src/core/definitions.dart b/lib/src/core/definitions.dart
index 82005aef..642038d1 100644
--- a/lib/src/core/definitions.dart
+++ b/lib/src/core/definitions.dart
@@ -14,6 +14,7 @@ library definitions;
 export "package:dcaf/dcaf.dart" show AuthServerRequestCreationHint;
 
 export "definitions/additional_expected_response.dart";
+export "definitions/context.dart";
 
 export "definitions/credentials/ace_credentials.dart";
 export "definitions/credentials/apikey_credentials.dart";
diff --git a/lib/src/core/definitions/data_schema.dart b/lib/src/core/definitions/data_schema.dart
index ca9cc0b7..3eb9c2c4 100644
--- a/lib/src/core/definitions/data_schema.dart
+++ b/lib/src/core/definitions/data_schema.dart
@@ -30,8 +30,8 @@ class DataSchema implements Serializable {
     this.unit,
     this.oneOf,
     this.enumeration,
-    this.readOnly = false,
-    this.writeOnly = false,
+    bool? readOnly,
+    bool? writeOnly,
     this.format,
     this.type,
     this.minimum,
@@ -50,7 +50,8 @@ class DataSchema implements Serializable {
     this.contentEncoding,
     this.contentMediaType,
     this.additionalFields = const {},
-  });
+  })  : readOnly = readOnly ?? _defaultReadOnly,
+        writeOnly = writeOnly ?? _defaultWriteOnly;
 
   // TODO: Consider creating separate classes for each data type.
   //       Also see https://github.com/w3c/wot-thing-description/issues/1390
@@ -142,6 +143,10 @@ class DataSchema implements Serializable {
     );
   }
 
+  static const _defaultWriteOnly = false;
+
+  static const _defaultReadOnly = false;
+
   /// JSON-LD keyword (@type) to label the object with semantic tags (or types).
   final List<String>? atType;
 
@@ -175,10 +180,10 @@ class DataSchema implements Serializable {
   final List<Object?>? enumeration;
 
   /// Indicates if a value is read only.
-  final bool? readOnly;
+  final bool readOnly;
 
   /// Indicates if a value is write only.
-  final bool? writeOnly;
+  final bool writeOnly;
 
   /// Allows validation based on a format pattern.
   ///
@@ -292,8 +297,6 @@ class DataSchema implements Serializable {
       ("const", constant),
       ("default", defaultValue),
       ("enum", enumeration),
-      ("readOnly", readOnly),
-      ("writeOnly", writeOnly),
       ("format", format),
       ("unit", unit),
       ("type", type),
@@ -332,6 +335,17 @@ class DataSchema implements Serializable {
       result[key] = convertedValue;
     }
 
+    final keyValuePairsWithDefault = [
+      ("readOnly", readOnly, _defaultReadOnly),
+      ("writeOnly", writeOnly, _defaultWriteOnly),
+    ];
+
+    for (final (key, value, defaultValue) in keyValuePairsWithDefault) {
+      if (value != defaultValue) {
+        result[key] = value;
+      }
+    }
+
     return result;
   }
 }
diff --git a/lib/src/core/definitions/form.dart b/lib/src/core/definitions/form.dart
index bd514d4c..425cc8e5 100644
--- a/lib/src/core/definitions/form.dart
+++ b/lib/src/core/definitions/form.dart
@@ -21,7 +21,7 @@ class Form implements Serializable {
   /// An [href] has to be provided. A [contentType] is optional.
   Form(
     this.href, {
-    this.contentType = "application/json",
+    this.contentType = _defaultContentType,
     this.contentCoding,
     this.subprotocol,
     this.security,
@@ -86,6 +86,8 @@ class Form implements Serializable {
     );
   }
 
+  static const _defaultContentType = "application/json";
+
   /// The [href] pointing to the resource.
   ///
   /// Can be a relative or absolute URI.
@@ -134,7 +136,6 @@ class Form implements Serializable {
   Map<String, dynamic> toJson() {
     final result = {
       "href": href.toString(),
-      "contentType": contentType,
       ...additionalFields,
     };
 
@@ -148,6 +149,10 @@ class Form implements Serializable {
           op.map((opValue) => opValue.toString()).toList(growable: false);
     }
 
+    if (contentType != _defaultContentType) {
+      result["contentType"] = contentType;
+    }
+
     if (contentCoding != null) {
       result["contentCoding"] = contentCoding;
     }
diff --git a/lib/src/core/definitions/interaction_affordances/property.dart b/lib/src/core/definitions/interaction_affordances/property.dart
index 39bde37a..3566e6f2 100644
--- a/lib/src/core/definitions/interaction_affordances/property.dart
+++ b/lib/src/core/definitions/interaction_affordances/property.dart
@@ -15,7 +15,7 @@ class Property extends InteractionAffordance implements DataSchema {
     super.uriVariables,
     super.additionalFields,
     required this.dataSchema,
-    this.observable = false,
+    this.observable = _defaultObservableValue,
   });
 
   /// Creates a new [Property] from a [json] object.
@@ -51,6 +51,22 @@ class Property extends InteractionAffordance implements DataSchema {
     return property;
   }
 
+  @override
+  Map<String, dynamic> toJson() {
+    final result = {
+      ...super.toJson(),
+      ...dataSchema.toJson(),
+    };
+
+    if (observable != _defaultObservableValue) {
+      result["observable"] = observable;
+    }
+
+    return result;
+  }
+
+  static const _defaultObservableValue = false;
+
   /// The internal [DataSchema] this property is based on.
   final DataSchema dataSchema;
 
@@ -85,7 +101,7 @@ class Property extends InteractionAffordance implements DataSchema {
   List<DataSchema>? get oneOf => dataSchema.oneOf;
 
   @override
-  bool get readOnly => dataSchema.readOnly ?? false;
+  bool get readOnly => dataSchema.readOnly;
 
   @override
   String? get type => dataSchema.type;
@@ -94,7 +110,7 @@ class Property extends InteractionAffordance implements DataSchema {
   String? get unit => dataSchema.unit;
 
   @override
-  bool get writeOnly => dataSchema.writeOnly ?? false;
+  bool get writeOnly => dataSchema.writeOnly;
 
   @override
   String? get contentEncoding => dataSchema.contentEncoding;
@@ -148,8 +164,15 @@ class Property extends InteractionAffordance implements DataSchema {
 
   @override
   Map<String, dynamic> get additionalFields {
-    final additionalDataSchemaFields = dataSchema.additionalFields.entries
-        .where((entry) => super.additionalFields.containsKey(entry.key));
+    final additionalDataSchemaFields =
+        dataSchema.additionalFields.entries.where(
+      (entry) => [
+        ...super.additionalFields.keys,
+        "observable",
+      ].contains(
+        entry.key,
+      ),
+    );
 
     return Map.fromEntries(additionalDataSchemaFields);
   }
diff --git a/lib/src/core/definitions/thing_description.dart b/lib/src/core/definitions/thing_description.dart
index b88553ea..caf46477 100644
--- a/lib/src/core/definitions/thing_description.dart
+++ b/lib/src/core/definitions/thing_description.dart
@@ -23,7 +23,7 @@ import "version_info.dart";
 @immutable
 class ThingDescription {
   /// Creates a new Thing Description object.
-  const ThingDescription._({
+  const ThingDescription({
     required this.context,
     required this.title,
     required this.security,
@@ -114,7 +114,7 @@ class ThingDescription {
     final additionalFields =
         json.parseAdditionalFields(prefixMapping, parsedFields);
 
-    return ThingDescription._(
+    return ThingDescription(
       context: context,
       title: title,
       titles: titles,
diff --git a/lib/src/core/implementation/servient.dart b/lib/src/core/implementation/servient.dart
index d7d57da9..75435b7b 100644
--- a/lib/src/core/implementation/servient.dart
+++ b/lib/src/core/implementation/servient.dart
@@ -8,7 +8,6 @@ import "package:meta/meta.dart";
 import "package:uuid/uuid.dart";
 
 import "../definitions.dart";
-import "../definitions/context.dart";
 import "../exceptions.dart";
 import "../protocol_interfaces.dart";
 import "../scripting_api.dart" as scripting_api;
diff --git a/test/core/definitions/serialization_test.dart b/test/core/definitions/serialization_test.dart
index 0a7e7f4e..74615d13 100644
--- a/test/core/definitions/serialization_test.dart
+++ b/test/core/definitions/serialization_test.dart
@@ -38,8 +38,6 @@ void main() {
             "op": [
               "readmultipleproperties",
             ],
-            // TODO: Should defaults actually be set?
-            "contentType": "application/json",
           },
         ],
         "properties": {},
@@ -103,7 +101,6 @@ void main() {
         "href": "https://example.org",
         "subprotocol": "foobar",
         "contentCoding": "test",
-        "contentType": "application/json",
         "security": ["test"],
         "response": {
           "contentType": "application/json",
@@ -123,7 +120,6 @@ void main() {
     test("AugmentedForms", () async {
       final formJson = {
         "href": "https://example.org",
-        "contentType": "application/json",
       };
 
       final thingDescription = {
@@ -186,7 +182,6 @@ void main() {
         "forms": [
           {
             "href": "https://example.org",
-            "contentType": "application/json",
           }
         ],
       };
diff --git a/test/core/definitions_test.dart b/test/core/definitions_test.dart
index 418afe49..1441a44f 100644
--- a/test/core/definitions_test.dart
+++ b/test/core/definitions_test.dart
@@ -8,7 +8,6 @@ import "dart:convert";
 
 import "package:curie/curie.dart";
 import "package:dart_wot/core.dart";
-import "package:dart_wot/src/core/definitions/context.dart";
 import "package:dart_wot/src/core/definitions/extensions/json_parser.dart";
 import "package:test/test.dart";
 
diff --git a/test/core/servient_test.dart b/test/core/servient_test.dart
index 5d01d403..12ec7070 100644
--- a/test/core/servient_test.dart
+++ b/test/core/servient_test.dart
@@ -5,7 +5,6 @@
 // SPDX-License-Identifier: BSD-3-Clause
 
 import "package:dart_wot/core.dart";
-import "package:dart_wot/src/core/definitions/context.dart";
 import "package:dart_wot/src/core/implementation/servient.dart";
 import "package:test/test.dart";
 
diff --git a/test/core/thing_description_test.dart b/test/core/thing_description_test.dart
index 20c72926..09a03877 100644
--- a/test/core/thing_description_test.dart
+++ b/test/core/thing_description_test.dart
@@ -39,6 +39,74 @@ void main() {
       expect(thingDescriptionJson, thingDescription.toJson());
     });
 
+    test(
+        "be able to be created via its constructor and converted to a "
+        "Map<String, dynamic>", () {
+      const thingDescriptionJson = {
+        "@context": [
+          "https://www.w3.org/2022/wot/td/v1.1",
+          {"@language": "de"},
+        ],
+        "title": "Test Thing",
+        "securityDefinitions": {
+          "nosec_sc": {"scheme": "nosec"},
+        },
+        "security": ["nosec_sc"],
+        "properties": {
+          "status": {
+            "type": "string",
+            "readOnly": true,
+            "observable": true,
+            "forms": [
+              {
+                "href": "https://example.org",
+                "contentType": "application/cbor",
+              }
+            ],
+          },
+        },
+      };
+
+      final thingDescription = ThingDescription(
+        context: Context(
+          [
+            SingleContextEntry(
+              Uri.parse("https://www.w3.org/2022/wot/td/v1.1"),
+            ),
+            const StringMapContextEntry(
+              "@language",
+              "de",
+            ),
+          ],
+        ),
+        title: "Test Thing",
+        security: const [
+          "nosec_sc",
+        ],
+        securityDefinitions: const {
+          "nosec_sc": NoSecurityScheme(),
+        },
+        properties: {
+          "status": Property(
+            forms: [
+              Form(
+                Uri.parse("https://example.org"),
+                contentType: "application/cbor",
+              ),
+            ],
+            observable: true,
+            dataSchema: const DataSchema(
+              type: "string",
+              readOnly: true,
+              writeOnly: false,
+            ),
+          ),
+        },
+      );
+
+      expect(thingDescriptionJson, thingDescription.toJson());
+    });
+
     test("throw a FormatException when it is invalid during parsing", () {
       const thingDescriptionJson = {
         "@context": [