diff --git a/.changeset/list-property-types.md b/.changeset/list-property-types.md
new file mode 100644
index 0000000..8abe388
--- /dev/null
+++ b/.changeset/list-property-types.md
@@ -0,0 +1,5 @@
+---
+"schema-utils": patch
+---
+
+output the type of object properties in error messages, i.e. `object { foo?: boolean, bar?: integer }`
diff --git a/src/ValidationError.js b/src/ValidationError.js
index a1296c6..ca7ddfb 100644
--- a/src/ValidationError.js
+++ b/src/ValidationError.js
@@ -423,6 +423,31 @@ function getArticle(type) {
   return "a";
 }
 
+// The constraints a formatted type ends with, they are stated by the error on
+// the property itself, so the summary of the shape does not repeat them
+const TYPE_CONSTRAINTS_REGEXP = /\s*\([^()]*\)$/;
+// A type that is more than a name: a union, an object or an array
+const COMPOSITE_TYPE_REGEXP = /[{}[\]()|\n]/;
+const MAX_LEAF_TYPE_LENGTH = 24;
+// The width the listed types of an object have to fit in
+const MAX_TYPED_STRUCTURE_LENGTH = 120;
+
+/**
+ * Names the type of a property shortly enough to sit next to the property name.
+ * A composite type is left out, it buries the property names it is listed with.
+ * @param {string} type formatted type
+ * @returns {string} the short name of the type, an empty string when it has none
+ */
+function getLeafTypeName(type) {
+  const name = type.replace(TYPE_CONSTRAINTS_REGEXP, "");
+
+  return name.length > 0 &&
+    name.length <= MAX_LEAF_TYPE_LENGTH &&
+    !COMPOSITE_TYPE_REGEXP.test(name)
+    ? name
+    : "";
+}
+
 /**
  * @param {Schema=} schema schema
  * @returns {string} schema non types
@@ -830,23 +855,45 @@ class ValidationError extends Error {
         ...new Set(/** @type {string[]} */ ([...required, ...properties])),
       ];
 
-      const objectStructure = [
-        ...allProperties.map((property) => {
-          const isRequired = required.includes(property);
-
-          // Some properties need quotes, maybe we should add check
-          // Maybe we should output type of property (`foo: string`), but it is looks very unreadable
-          return `${property}${isRequired ? "" : "?"}`;
-        }),
-        ...(typeof schema.additionalProperties === "undefined" ||
+      const namedProperties = allProperties.map((property) => {
+        // Some properties need quotes, maybe we should add check
+        const name = `${property}${required.includes(property) ? "" : "?"}`;
+        const propertySchema = schema.properties
+          ? schema.properties[property]
+          : undefined;
+        const type =
+          propertySchema && propertySchema !== true
+            ? getLeafTypeName(formatInnerSchema(propertySchema, true))
+            : "";
+
+        return { name, type };
+      });
+
+      const otherProperties =
+        typeof schema.additionalProperties === "undefined" ||
         Boolean(schema.additionalProperties)
           ? schema.additionalProperties &&
             isObject(schema.additionalProperties) &&
             schema.additionalProperties !== true
             ? [`<key>: ${formatInnerSchema(schema.additionalProperties)}`]
             : ["…"]
-          : []),
+          : [];
+
+      const typedStructure = [
+        ...namedProperties.map(
+          ({ name, type }) => `${name}${type ? `: ${type}` : ""}`,
+        ),
+        ...otherProperties,
       ].join(", ");
+      // The types are only listed while the shape stays readable, an object with
+      // that many properties is hard enough to read by the names alone
+      const objectStructure =
+        typedStructure.length <= MAX_TYPED_STRUCTURE_LENGTH
+          ? typedStructure
+          : [
+              ...namedProperties.map(({ name }) => name),
+              ...otherProperties,
+            ].join(", ");
 
       const { dependencies, propertyNames, patternRequired } =
         /** @type {Schema & { patternRequired?: string[] }} */ (schema);
diff --git a/test/__snapshots__/api.test.js.snap b/test/__snapshots__/api.test.js.snap
index ba53c33..790199a 100644
--- a/test/__snapshots__/api.test.js.snap
+++ b/test/__snapshots__/api.test.js.snap
@@ -3,55 +3,73 @@
 exports[`api should allow to enable validation using "process.env.SKIP_VALIDATION" #2 1`] = `
 "Invalid options object. NAME has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should allow to enable validation using "process.env.SKIP_VALIDATION" 1`] = `
 "Invalid options object. NAME has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should allow to enable validation using API 1`] = `
 "Invalid options object. NAME has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should get configuration from schema 1`] = `
 "Invalid options object. CSS Loader has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
+`;
+
+exports[`api should not output the type of a property when it is a composite one 1`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should be an object:
+   object { shorthand?: string, union?, nested?, list?, constrained?: number, … }"
+`;
+
+exports[`api should not output the types of an object with many properties 1`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should be an object:
+   object { property0?, property1?, property2?, property3?, property4?, property5?, property6?, property7?, property8?, property9?, property10?, property11?, property12?, property13?, property14?, property15?, property16?, property17?, property18?, property19?, … }"
+`;
+
+exports[`api should output the type of each property 1`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should be an object:
+   object { foo?: boolean, bar?: integer, … }"
 `;
 
 exports[`api should prefer configuration over "title" #1 1`] = `
 "Invalid options object. NAME has been initialized using an options object that does not match the API schema.
  - options has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should prefer configuration over "title" #2 1`] = `
 "Invalid BaseDataPath object. CSS Loader has been initialized using a BaseDataPath object that does not match the API schema.
  - BaseDataPath has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should prefer configuration over "title" 1`] = `
 "Invalid BaseDataPath object. NAME has been initialized using a BaseDataPath object that does not match the API schema.
  - BaseDataPath has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should use default values when "title" is broken 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration has an unknown property 'foo'. These properties are valid:
-   object { name? }"
+   object { name?: boolean }"
 `;
 
 exports[`api should work with anyOf 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration should be one of these:
-   object { bar, … } | object { baz, … }
+   object { bar: number, … } | object { baz: number, … }
    Details:
     * configuration misses the property 'bar' | should be any non-object. Should be:
       number
@@ -74,3 +92,18 @@ exports[`api should work with required properties 1`] = `
  - configuration.c misses the property 'e'. Should be:
    string"
 `;
+
+exports[`api should work with the \`not\` keyword 1`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should be any non-number | number (should be < 3)."
+`;
+
+exports[`api should work with the \`not\` keyword 2`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should be any non-string."
+`;
+
+exports[`api should work with the \`not\` keyword 3`] = `
+"Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
+ - configuration.v should not be 1 | 2."
+`;
diff --git a/test/__snapshots__/index.test.js.snap b/test/__snapshots__/index.test.js.snap
index d901c34..5c684d2 100644
--- a/test/__snapshots__/index.test.js.snap
+++ b/test/__snapshots__/index.test.js.snap
@@ -19,11 +19,11 @@ exports[`validation should fail validation for $data 1`] = `
 exports[`validation should fail validation for Invalid plugin provided: int 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.plugins[0] should be one of these:
-   object { apply, … } | function
+   object { apply: function, … } | function
    -> Plugin of type object or instanceof Function
    Details:
     * configuration.plugins[0] should be an object:
-      object { apply, … }
+      object { apply: function, … }
       -> Plugin instance
     * configuration.plugins[0] should be an instance of function.
       -> Function acting as plugin"
@@ -103,13 +103,13 @@ exports[`validation should fail validation for additionalItems with false 1`] =
 exports[`validation should fail validation for additionalProperties #2 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesKeyword has an unknown property 'baz' | should be any non-object. These properties are valid:
-   object { foo? } (additional property names should match pattern "^.*r$")"
+   object { foo?: number } (additional property names should match pattern "^.*r$")"
 `;
 
 exports[`validation should fail validation for additionalProperties #3 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesKeyword has an unknown property 'baz' | should be any non-object. These properties are valid:
-   object { foo? } (additional property names should match pattern "^.*r$")
+   object { foo?: number } (additional property names should match pattern "^.*r$")
  - configuration.additionalPropertiesKeyword.foo should be a number."
 `;
 
@@ -131,33 +131,33 @@ exports[`validation should fail validation for additionalProperties #6 1`] = `
 exports[`validation should fail validation for additionalProperties 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesKeyword has an unknown property 'a' | should be any non-object. These properties are valid:
-   object { foo? } (additional property names should match pattern "^.*r$")"
+   object { foo?: number } (additional property names should match pattern "^.*r$")"
 `;
 
 exports[`validation should fail validation for additionalProperties inside oneOf #2 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesInsideOneOf has an unknown property 'bar'. These properties are valid:
-   object { foo? }"
+   object { foo?: integer }"
 `;
 
 exports[`validation should fail validation for additionalProperties inside oneOf #3 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesInsideOneOf2 should be one of these:
-   integer (should be <= 3) | object { foo?, … }
+   integer (should be <= 3) | object { foo?: integer, … }
    Details:
     * configuration.additionalPropertiesInsideOneOf2 should be an integer (should be <= 3).
     * configuration.additionalPropertiesInsideOneOf2 should be an object:
-      object { foo?, … }"
+      object { foo?: integer, … }"
 `;
 
 exports[`validation should fail validation for additionalProperties inside oneOf 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.additionalPropertiesInsideOneOf should be one of these:
-   integer (should be <= 3) | object { foo? }
+   integer (should be <= 3) | object { foo?: integer }
    Details:
     * configuration.additionalPropertiesInsideOneOf should be an integer (should be <= 3).
     * configuration.additionalPropertiesInsideOneOf should be an object:
-      object { foo? }"
+      object { foo?: integer }"
 `;
 
 exports[`validation should fail validation for additionalProperties without object type 1`] = `
@@ -194,10 +194,10 @@ exports[`validation should fail validation for allOf 2`] = `
 exports[`validation should fail validation for anyOf 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.anyOfKeyword should be one of these:
-   object { foo?, … } | non-empty string | [non-empty string, ...] (should not have fewer than 1 item, should not have duplicate items)
+   object { foo?: string, … } | non-empty string | [non-empty string, ...] (should not have fewer than 1 item, should not have duplicate items)
    Details:
     * configuration.anyOfKeyword should be an object:
-      object { foo?, … }
+      object { foo?: string, … }
     * configuration.anyOfKeyword should be one of these:
       non-empty string | [non-empty string, ...] (should not have fewer than 1 item, should not have duplicate items)
       Details:
@@ -342,7 +342,7 @@ exports[`validation should fail validation for array #21 1`] = `
 exports[`validation should fail validation for array #22 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.arrayKeyword16 should be an array:
-   [integer, integer, ...] (should not have fewer than 4 items, should not have more than 8 items, additional items should be object { foo?, bar?, … })"
+   [integer, integer, ...] (should not have fewer than 4 items, should not have more than 8 items, additional items should be object { foo?: string, bar?: number, … })"
 `;
 
 exports[`validation should fail validation for array #23 1`] = `
@@ -932,11 +932,11 @@ exports[`validation should fail validation for invalid mode 1`] = `
 exports[`validation should fail validation for invalid plugin provided: array 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.plugins[0] should be one of these:
-   object { apply, … } | function
+   object { apply: function, … } | function
    -> Plugin of type object or instanceof Function
    Details:
     * configuration.plugins[0] should be an object:
-      object { apply, … }
+      object { apply: function, … }
       -> Plugin instance
     * configuration.plugins[0] should be an instance of function.
       -> Function acting as plugin"
@@ -945,11 +945,11 @@ exports[`validation should fail validation for invalid plugin provided: array 1`
 exports[`validation should fail validation for invalid plugin provided: bool 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.plugins[0] should be one of these:
-   object { apply, … } | function
+   object { apply: function, … } | function
    -> Plugin of type object or instanceof Function
    Details:
     * configuration.plugins[0] should be an object:
-      object { apply, … }
+      object { apply: function, … }
       -> Plugin instance
     * configuration.plugins[0] should be an instance of function.
       -> Function acting as plugin"
@@ -958,11 +958,11 @@ exports[`validation should fail validation for invalid plugin provided: bool 1`]
 exports[`validation should fail validation for invalid plugin provided: string 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.plugins[0] should be one of these:
-   object { apply, … } | function
+   object { apply: function, … } | function
    -> Plugin of type object or instanceof Function
    Details:
     * configuration.plugins[0] should be an object:
-      object { apply, … }
+      object { apply: function, … }
       -> Plugin instance
     * configuration.plugins[0] should be an instance of function.
       -> Function acting as plugin"
@@ -1039,7 +1039,7 @@ exports[`validation should fail validation for maxProperties and minProperties #
 exports[`validation should fail validation for maxProperties and minProperties 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.maxPropertiesAndMinProperties should be an object:
-   object { foo?, bar?, … } (should not have fewer than 3 properties, should not have more than 5 properties)"
+   object { foo?: string, bar?: number, … } (should not have fewer than 3 properties, should not have more than 5 properties)"
 `;
 
 exports[`validation should fail validation for maxProperties without object type 1`] = `
@@ -1258,7 +1258,7 @@ exports[`validation should fail validation for no type like number with multiple
 exports[`validation should fail validation for no type like object additionalProperties 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.noTypeLikeObjectAdditionalProperties has an unknown property 'baz' | should be any non-object. These properties are valid:
-   object { foo? } (additional property names should match pattern "^.*r$")"
+   object { foo?: number } (additional property names should match pattern "^.*r$")"
 `;
 
 exports[`validation should fail validation for no type like object dependencies 1`] = `
@@ -1330,7 +1330,7 @@ exports[`validation should fail validation for non empty object #2 1`] = `
 exports[`validation should fail validation for non empty object 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.nonEmptyObject should be an object:
-   object { bar? }"
+   object { bar?: number }"
 `;
 
 exports[`validation should fail validation for non empty string in object with anyOf 1`] = `
@@ -1446,7 +1446,7 @@ exports[`validation should fail validation for number with minimum and maximum 1
 exports[`validation should fail validation for object #2 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectTest2 should be an object:
-   object { a, b, c, d } (should not have fewer than 3 properties, should not have more than 5 properties)"
+   object { a: number, b: number, c: number, d } (should not have fewer than 3 properties, should not have more than 5 properties)"
 `;
 
 exports[`validation should fail validation for object #3 1`] = `
@@ -1475,7 +1475,7 @@ exports[`validation should fail validation for object #6 1`] = `
 exports[`validation should fail validation for object #7 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectTest5 should be an object:
-   object { foo@bar.com, <key>: string } (each property name should match format "email")"
+   object { foo@bar.com: number, <key>: string } (each property name should match format "email")"
 `;
 
 exports[`validation should fail validation for object #8 1`] = `
@@ -1487,7 +1487,7 @@ exports[`validation should fail validation for object #8 1`] = `
 exports[`validation should fail validation for object #9 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectTest7 should be an object:
-   object { prop, … } (should have properties 'bar', 'baz' when property 'foo' is present, should be valid according to the schema object { a, b, c, d, bar?, … } when property 'baz' is present)"
+   object { prop, … } (should have properties 'bar', 'baz' when property 'foo' is present, should be valid according to the schema object { a, b, c, d, bar?: number, … } when property 'baz' is present)"
 `;
 
 exports[`validation should fail validation for object #9 2`] = `
@@ -1505,7 +1505,7 @@ exports[`validation should fail validation for object #10 1`] = `
 exports[`validation should fail validation for object #11 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectTest9 should be an object:
-   object { prop, … } (should have properties 'bar', 'baz' when property 'foo' is present, should be valid according to the schema object { other, prop, bar?, … } when property 'baz' is present)"
+   object { prop, … } (should have properties 'bar', 'baz' when property 'foo' is present, should be valid according to the schema object { other, prop, bar?: number, … } when property 'baz' is present)"
 `;
 
 exports[`validation should fail validation for object #12 1`] = `
@@ -1517,7 +1517,7 @@ exports[`validation should fail validation for object #12 1`] = `
 exports[`validation should fail validation for object 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectTest should be an object:
-   object { a, b, c, d, f?, <key>: number } (should not have fewer than 3 properties, should not have more than 5 properties)"
+   object { a: number, b: number, c: number, d, f?: number, <key>: number } (should not have fewer than 3 properties, should not have more than 5 properties)"
 `;
 
 exports[`validation should fail validation for object dependencies 1`] = `
@@ -1533,13 +1533,13 @@ exports[`validation should fail validation for object dependencies 2`] = `
 exports[`validation should fail validation for object in object with anyOf 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.allOfRef.alias should be one of these:
-   object { <key>: string } | [object { alias?, name?, onlyModule? }, ...]
+   object { <key>: string } | [object { alias?: string, name?: string, onlyModule?: boolean }, ...]
    -> Redirect module requests
    Details:
     * configuration.allOfRef.alias should be an object:
       object { <key>: string }
     * configuration.allOfRef.alias should be an array:
-      [object { alias?, name?, onlyModule? }, ...]"
+      [object { alias?: string, name?: string, onlyModule?: boolean }, ...]"
 `;
 
 exports[`validation should fail validation for object type 1`] = `
@@ -1552,25 +1552,25 @@ exports[`validation should fail validation for object type 1`] = `
 exports[`validation should fail validation for object with dependencies #2 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectWithPropertyDependency2 should be an object:
-   object { foo?, … } (should have property 'bar' when property 'foo' is present)"
+   object { foo?: string, … } (should have property 'bar' when property 'foo' is present)"
 `;
 
 exports[`validation should fail validation for object with dependencies #3 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectWithPropertyDependency3 should be an object:
-   object { foo?, … } (should be valid according to the schema object { bar?, … } when property 'foo' is present)"
+   object { foo?: string, … } (should be valid according to the schema object { bar?: number, … } when property 'foo' is present)"
 `;
 
 exports[`validation should fail validation for object with dependencies #4 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectWithPropertyDependency4 should be an object:
-   object { foo?, … }"
+   object { foo?: string, … }"
 `;
 
 exports[`validation should fail validation for object with dependencies 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.objectWithPropertyDependency should be an object:
-   object { foo?, … } (should have properties 'bar', 'baz' when property 'foo' is present)"
+   object { foo?: string, … } (should have properties 'bar', 'baz' when property 'foo' is present)"
 `;
 
 exports[`validation should fail validation for object with maxProperties 1`] = `
@@ -1586,7 +1586,7 @@ exports[`validation should fail validation for object with maxProperties 2`] = `
 exports[`validation should fail validation for object with required and properties 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.justAnObject should be an object:
-   object { foo, bar?, … }"
+   object { foo: string, bar?: number, … }"
 `;
 
 exports[`validation should fail validation for object without items 1`] = `
@@ -1665,10 +1665,10 @@ exports[`validation should fail validation for oneOf with description 1`] = `
 exports[`validation should fail validation for oneOf with if 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.oneOfWithIf should be one of these:
-   if object { power?, … } then object { disbelief, … } else object { confidence, … } | integer
+   if object { power?: number, … } then object { disbelief, … } else object { confidence, … } | integer
    Details:
     * configuration.oneOfWithIf should be an object:
-      if object { power?, … } then object { disbelief, … } else object { confidence, … }
+      if object { power?: number, … } then object { disbelief, … } else object { confidence, … }
     * configuration.oneOfWithIf should be an integer."
 `;
 
@@ -1691,7 +1691,7 @@ exports[`validation should fail validation for only items 1`] = `
 exports[`validation should fail validation for only properties #2 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.onlyProperties2 has an unknown property 'break' | should be any non-object. These properties are valid:
-   object { foo?, bar? }"
+   object { foo?: string, bar?: number }"
 `;
 
 exports[`validation should fail validation for only properties 1`] = `
@@ -1803,7 +1803,7 @@ exports[`validation should fail validation for propertyNames without object type
 exports[`validation should fail validation for recursion 1`] = `
 "Invalid configuration object. Object has been initialized using a configuration object that does not match the API schema.
  - configuration.recursion.person.children should be an array:
-   [object { name?, children?, … }, ...]"
+   [object { name?: string, children?, … }, ...]"
 `;
 
 exports[`validation should fail validation for ref inside object inside allOf 1`] = `
diff --git a/test/api.test.js b/test/api.test.js
index ef15e96..33d852c 100644
--- a/test/api.test.js
+++ b/test/api.test.js
@@ -198,6 +198,111 @@ describe("api", () => {
     }
   });
 
+  it("should output the type of each property", () => {
+    expect.assertions(1);
+
+    try {
+      validate(
+        {
+          type: "object",
+          properties: {
+            v: {
+              type: "object",
+              properties: {
+                foo: { type: "boolean" },
+                bar: { type: "integer" },
+              },
+            },
+          },
+        },
+        { v: 1 },
+      );
+    } catch (error) {
+      if (error.name !== "ValidationError") {
+        throw error;
+      }
+
+      expect(error.message).toMatchSnapshot();
+    }
+  });
+
+  it("should not output the type of a property when it is a composite one", () => {
+    expect.assertions(1);
+
+    try {
+      validate(
+        {
+          type: "object",
+          properties: {
+            v: {
+              type: "object",
+              properties: {
+                shorthand: { type: "string" },
+                union: { type: ["string", "number"] },
+                nested: {
+                  type: "object",
+                  properties: { deep: { type: "string" } },
+                },
+                list: { type: "array", items: { type: "string" } },
+                constrained: { type: "number", minimum: 2 },
+              },
+            },
+          },
+        },
+        { v: 1 },
+      );
+    } catch (error) {
+      if (error.name !== "ValidationError") {
+        throw error;
+      }
+
+      expect(error.message).toMatchSnapshot();
+    }
+  });
+
+  it("should not output the types of an object with many properties", () => {
+    expect.assertions(1);
+
+    const properties = {};
+
+    for (let i = 0; i < 20; i++) {
+      properties[`property${i}`] = { type: "string" };
+    }
+
+    try {
+      validate(
+        { type: "object", properties: { v: { type: "object", properties } } },
+        { v: 1 },
+      );
+    } catch (error) {
+      if (error.name !== "ValidationError") {
+        throw error;
+      }
+
+      expect(error.message).toMatchSnapshot();
+    }
+  });
+
+  it("should work with the `not` keyword", () => {
+    expect.assertions(3);
+
+    for (const [not, value] of [
+      [{ minimum: 3 }, 5],
+      [{ type: "string" }, "foo"],
+      [{ enum: [1, 2] }, 1],
+    ]) {
+      try {
+        validate({ type: "object", properties: { v: { not } } }, { v: value });
+      } catch (error) {
+        if (error.name !== "ValidationError") {
+          throw error;
+        }
+
+        expect(error.message).toMatchSnapshot();
+      }
+    }
+  });
+
   it("should work with minProperties properties", () => {
     try {
       validate(