diff --git a/tools/spectral/ipa/__tests__/IPA111EffectiveFieldsReadOnly.test.js b/tools/spectral/ipa/__tests__/IPA111EffectiveFieldsReadOnly.test.js
new file mode 100644
index 0000000000..ba2b5f3820
--- /dev/null
+++ b/tools/spectral/ipa/__tests__/IPA111EffectiveFieldsReadOnly.test.js
@@ -0,0 +1,146 @@
+import testRule from './__helpers__/testRule';
+import { DiagnosticSeverity } from '@stoplight/types';
+
+testRule('xgen-IPA-111-effective-fields-read-only', [
+  {
+    name: 'valid effective field with readOnly: true',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              effectiveState: { type: 'string', readOnly: true },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid non-effective field without readOnly',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              state: { type: 'string' },
+              effective: { type: 'string' },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid effective field without readOnly',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              effectiveState: { type: 'string' },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-effective-fields-read-only',
+        message: 'Effective-value fields must be marked as readOnly: true.',
+        path: ['components', 'schemas', 'Schema', 'properties', 'effectiveState'],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid effective field with readOnly: false',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              effectiveState: { type: 'string', readOnly: false },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-effective-fields-read-only',
+        message: 'Effective-value fields must be marked as readOnly: true.',
+        path: ['components', 'schemas', 'Schema', 'properties', 'effectiveState'],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid effective field in request schema',
+    document: {
+      paths: {
+        '/resources': {
+          post: {
+            requestBody: {
+              content: {
+                'application/vnd.atlas.2024-01-01+json': {
+                  schema: {
+                    type: 'object',
+                    properties: {
+                      effectiveState: { type: 'string', readOnly: true },
+                    },
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-effective-fields-read-only',
+        message: 'Effective-value fields represent server-computed state and must not appear in request schemas.',
+        path: [
+          'paths',
+          '/resources',
+          'post',
+          'requestBody',
+          'content',
+          'application/vnd.atlas.2024-01-01+json',
+          'schema',
+          'properties',
+          'effectiveState',
+        ],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid effective field without readOnly - exception',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              effectiveState: {
+                type: 'string',
+                'x-xgen-IPA-exception': {
+                  'xgen-IPA-111-effective-fields-read-only': 'Reason',
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+]);
diff --git a/tools/spectral/ipa/__tests__/IPA111OptionalBooleanFieldsDefaultFalse.test.js b/tools/spectral/ipa/__tests__/IPA111OptionalBooleanFieldsDefaultFalse.test.js
new file mode 100644
index 0000000000..4512d78d52
--- /dev/null
+++ b/tools/spectral/ipa/__tests__/IPA111OptionalBooleanFieldsDefaultFalse.test.js
@@ -0,0 +1,193 @@
+import testRule from './__helpers__/testRule';
+import { DiagnosticSeverity } from '@stoplight/types';
+
+testRule('xgen-IPA-111-optional-boolean-fields-default-false', [
+  {
+    name: 'valid optional boolean field with default false',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              enabled: { type: 'boolean', default: false },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid required boolean field without default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            required: ['enabled'],
+            properties: {
+              enabled: { type: 'boolean' },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid non-boolean field without default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              name: { type: 'string' },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid optional boolean field without default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              enabled: { type: 'boolean' },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-optional-boolean-fields-default-false',
+        message: 'Optional boolean fields must default to false.',
+        path: ['components', 'schemas', 'Schema', 'properties', 'enabled'],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid optional boolean field with default true',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              enabled: { type: 'boolean', default: true },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-optional-boolean-fields-default-false',
+        message: 'Optional boolean fields must default to false.',
+        path: ['components', 'schemas', 'Schema', 'properties', 'enabled'],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid optional boolean field in request and response',
+    document: {
+      paths: {
+        '/resources': {
+          post: {
+            requestBody: {
+              content: {
+                'application/vnd.atlas.2024-01-01+json': {
+                  schema: {
+                    type: 'object',
+                    properties: {
+                      paused: { type: 'boolean' },
+                    },
+                  },
+                },
+              },
+            },
+            responses: {
+              201: {
+                content: {
+                  'application/vnd.atlas.2024-01-01+json': {
+                    schema: {
+                      type: 'object',
+                      properties: {
+                        hidden: { type: 'boolean', default: true },
+                      },
+                    },
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-optional-boolean-fields-default-false',
+        message: 'Optional boolean fields must default to false.',
+        path: [
+          'paths',
+          '/resources',
+          'post',
+          'requestBody',
+          'content',
+          'application/vnd.atlas.2024-01-01+json',
+          'schema',
+          'properties',
+          'paused',
+        ],
+        severity: DiagnosticSeverity.Error,
+      },
+      {
+        code: 'xgen-IPA-111-optional-boolean-fields-default-false',
+        message: 'Optional boolean fields must default to false.',
+        path: [
+          'paths',
+          '/resources',
+          'post',
+          'responses',
+          '201',
+          'content',
+          'application/vnd.atlas.2024-01-01+json',
+          'schema',
+          'properties',
+          'hidden',
+        ],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid optional boolean field without default - exception',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              enabled: {
+                type: 'boolean',
+                'x-xgen-IPA-exception': {
+                  'xgen-IPA-111-optional-boolean-fields-default-false': 'Reason',
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+]);
diff --git a/tools/spectral/ipa/__tests__/IPA111OptionalFieldsNoDefault.test.js b/tools/spectral/ipa/__tests__/IPA111OptionalFieldsNoDefault.test.js
new file mode 100644
index 0000000000..fb320c0f1b
--- /dev/null
+++ b/tools/spectral/ipa/__tests__/IPA111OptionalFieldsNoDefault.test.js
@@ -0,0 +1,194 @@
+import testRule from './__helpers__/testRule';
+import { DiagnosticSeverity } from '@stoplight/types';
+
+testRule('xgen-IPA-111-optional-fields-no-default', [
+  {
+    name: 'valid optional field without default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              name: { type: 'string' },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid required field with default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            required: ['name'],
+            properties: {
+              name: { type: 'string', default: 'value' },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid optional field with default and server-computed extension',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              name: {
+                type: 'string',
+                default: 'value',
+                'x-xgen-server-computed-when-client-omitted': true,
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'valid optional boolean field with default (handled by other rule)',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              enabled: { type: 'boolean', default: true },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid optional field with default',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              name: { type: 'string', default: 'value' },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-optional-fields-no-default',
+        message:
+          'Optional fields must not define a default value. Remove the default or mark the field with x-xgen-server-computed-when-client-omitted if the server computes it when omitted.',
+        path: ['components', 'schemas', 'Schema', 'properties', 'name'],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid optional field with default in request and response',
+    document: {
+      paths: {
+        '/resources': {
+          post: {
+            requestBody: {
+              content: {
+                'application/vnd.atlas.2024-01-01+json': {
+                  schema: {
+                    type: 'object',
+                    properties: {
+                      size: { type: 'integer', default: 5 },
+                    },
+                  },
+                },
+              },
+            },
+            responses: {
+              201: {
+                content: {
+                  'application/vnd.atlas.2024-01-01+json': {
+                    schema: {
+                      type: 'object',
+                      properties: {
+                        region: { type: 'string', default: 'US_EAST' },
+                      },
+                    },
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-111-optional-fields-no-default',
+        message:
+          'Optional fields must not define a default value. Remove the default or mark the field with x-xgen-server-computed-when-client-omitted if the server computes it when omitted.',
+        path: [
+          'paths',
+          '/resources',
+          'post',
+          'requestBody',
+          'content',
+          'application/vnd.atlas.2024-01-01+json',
+          'schema',
+          'properties',
+          'size',
+        ],
+        severity: DiagnosticSeverity.Error,
+      },
+      {
+        code: 'xgen-IPA-111-optional-fields-no-default',
+        message:
+          'Optional fields must not define a default value. Remove the default or mark the field with x-xgen-server-computed-when-client-omitted if the server computes it when omitted.',
+        path: [
+          'paths',
+          '/resources',
+          'post',
+          'responses',
+          '201',
+          'content',
+          'application/vnd.atlas.2024-01-01+json',
+          'schema',
+          'properties',
+          'region',
+        ],
+        severity: DiagnosticSeverity.Error,
+      },
+    ],
+  },
+  {
+    name: 'invalid optional field with default - exception',
+    document: {
+      components: {
+        schemas: {
+          Schema: {
+            type: 'object',
+            properties: {
+              name: {
+                type: 'string',
+                default: 'value',
+                'x-xgen-IPA-exception': {
+                  'xgen-IPA-111-optional-fields-no-default': 'Reason',
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+]);
diff --git a/tools/spectral/ipa/ipa-spectral.yaml b/tools/spectral/ipa/ipa-spectral.yaml
index e15fff8b6f..ab6bcfc605 100644
--- a/tools/spectral/ipa/ipa-spectral.yaml
+++ b/tools/spectral/ipa/ipa-spectral.yaml
@@ -8,6 +8,7 @@ extends:
   - ./rulesets/IPA-108.yaml
   - ./rulesets/IPA-109.yaml
   - ./rulesets/IPA-110.yaml
+  - ./rulesets/IPA-111.yaml
   - ./rulesets/IPA-112.yaml
   - ./rulesets/IPA-113.yaml
   - ./rulesets/IPA-114.yaml
@@ -89,3 +90,76 @@ overrides:
     rules:
       xgen-IPA-107-operation-id-length: 'off'
       xgen-IPA-107-valid-operation-id: 'off'
+  - files:
+      - '**#/components/schemas/S3LogIntegrationRequest/allOf/1/properties/useLegacyPathStructure' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/S3LogIntegrationResponse/allOf/1/properties/useLegacyPathStructure' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SandboxConfigRequest/properties/enabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SandboxConfigResponse/properties/enabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SandboxConfigUpdateRequest/properties/enabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchDeploymentAuditView/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchHostStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchIndexResponse/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchMainIndexStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchStagedIndexStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/ServiceAccountGroupEvents/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/ServiceAccountOrgEvents/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsAutoscaling/properties/enabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsModifyStreamProcessor/properties/failoverEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsModifyStreamProcessorOptions/properties/resumeFromCheckpoint' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsProcessor/properties/failoverEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsProcessorWithStats/properties/eligibleForFailover' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsProcessorWithStats/properties/failoverEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsStartProcessorFailover/properties/clearCheckpoint' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsStartProcessorFailover/properties/dryRun' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/StreamsStartStreamProcessorWith/properties/resumeFromCheckpoint' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SynonymMappingStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TeamEvent/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TeamEventViewForNdsGroup/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TeamNotification/properties/emailEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TeamNotification/properties/smsEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TextSearchHostStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TextSearchIndexStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TimeMetricEventView/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/generateNumberParts' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/generateWordParts' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/preserveOriginal' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/splitOnCaseChange' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/splitOnNumerics' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/delimiterOptions/properties/stemEnglishPossessive' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TokenFilterWordDelimiterGraph/properties/protectedWords/properties/ignoreCase' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UsageDetailsFilterRequest/properties/includeZeroCentLineItems' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UserEventViewForNdsGroup/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UserEventViewForOrg/properties/isGlobalAdmin' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UserNotification/properties/emailEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UserNotification/properties/smsEnabled' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/VectorSearchHostStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/VectorSearchIndexStatusDetail/properties/queryable' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilterstopword/properties/ignoreCase' # to be addressed in CLOUDP-439952
+    rules:
+      xgen-IPA-111-optional-boolean-fields-default-false: 'off'
+  - files:
+      - '**#/components/schemas/SearchIndex/allOf/1/properties/analyzer' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchIndex/allOf/1/properties/searchAnalyzer' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/SearchIndexDefinition/properties/numPartitions' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/ServerlessProviderSettings/properties/providerName' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TextSearchIndexDefinition/properties/analyzer' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TextSearchIndexDefinition/properties/numPartitions' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/TextSearchIndexDefinition/properties/searchAnalyzer' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/UserCert/properties/monthsUntilExpiration' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/VectorSearchIndexDefinition/properties/numPartitions' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilterasciiFolding/properties/originalTokens' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilterdaitchMokotoffSoundex/properties/originalTokens' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilteredgeGram/properties/termNotInBounds' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFiltericuNormalizer/properties/normalizationForm' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilterlength/properties/max' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilterlength/properties/min' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenFilternGram/properties/termNotInBounds' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenizerstandard/properties/maxTokenLength' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenizeruaxUrlEmail/properties/maxTokenLength' # to be addressed in CLOUDP-439952
+      - '**#/components/schemas/tokenizerwhitespace/properties/maxTokenLength' # to be addressed in CLOUDP-439952
+    rules:
+      xgen-IPA-111-optional-fields-no-default: 'off'
+  - files:
+      - '**#/components/schemas/ServerlessProviderSettings/properties/effectiveInstanceSizeName' # to be addressed in CLOUDP-439952
+    rules:
+      xgen-IPA-111-effective-fields-read-only: 'off'
diff --git a/tools/spectral/ipa/rulesets/IPA-111.yaml b/tools/spectral/ipa/rulesets/IPA-111.yaml
new file mode 100644
index 0000000000..c3f3ffece6
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/IPA-111.yaml
@@ -0,0 +1,66 @@
+# IPA-111: Default Values
+# https://mongodb.github.io/ipa/111
+
+functions:
+  - IPA111OptionalFieldsNoDefault
+  - IPA111EffectiveFieldsReadOnly
+  - IPA111OptionalBooleanFieldsDefaultFalse
+
+rules:
+  xgen-IPA-111-optional-fields-no-default:
+    description: |
+      Optional fields must not define a default value.
+
+      ##### Implementation details
+      Rule checks for the following conditions:
+        - Applies to optional (non-required) schema properties in components, request bodies and responses
+        - Boolean fields are exempt (covered by xgen-IPA-111-optional-boolean-fields-default-false)
+        - Fields marked with the x-xgen-server-computed-when-client-omitted extension are exempt
+        - Fails if the field defines a default value
+    message: '{{error}} https://mdb.link/mongodb-atlas-openapi-validation#xgen-IPA-111-optional-fields-no-default'
+    severity: error
+    resolved: false
+    given:
+      - '$.components.schemas..properties'
+      - '$.paths..requestBody.content[?(@property.match(/json$/i))].schema..properties'
+      - '$.paths..responses..content[?(@property.match(/json$/i))].schema..properties'
+    then:
+      field: '@key'
+      function: 'IPA111OptionalFieldsNoDefault'
+  xgen-IPA-111-effective-fields-read-only:
+    description: |
+      Effective-value fields must be marked as readOnly: true and must not appear in request schemas.
+
+      ##### Implementation details
+      Rule checks for the following conditions:
+        - Applies to schema properties whose name starts with the "effective" prefix
+        - Fails if the field appears in a request schema
+        - Fails if the field is not marked with readOnly: true
+    message: '{{error}} https://mdb.link/mongodb-atlas-openapi-validation#xgen-IPA-111-effective-fields-read-only'
+    severity: error
+    resolved: false
+    given:
+      - '$.components.schemas..properties'
+      - '$.paths..requestBody.content[?(@property.match(/json$/i))].schema..properties'
+      - '$.paths..responses..content[?(@property.match(/json$/i))].schema..properties'
+    then:
+      field: '@key'
+      function: 'IPA111EffectiveFieldsReadOnly'
+  xgen-IPA-111-optional-boolean-fields-default-false:
+    description: |
+      Optional boolean fields must default to false.
+
+      ##### Implementation details
+      Rule checks for the following conditions:
+        - Applies to optional (non-required) boolean schema properties in components, request bodies and responses
+        - Fails if the field does not define a default value of false
+    message: '{{error}} https://mdb.link/mongodb-atlas-openapi-validation#xgen-IPA-111-optional-boolean-fields-default-false'
+    severity: error
+    resolved: false
+    given:
+      - '$.components.schemas..properties'
+      - '$.paths..requestBody.content[?(@property.match(/json$/i))].schema..properties'
+      - '$.paths..responses..content[?(@property.match(/json$/i))].schema..properties'
+    then:
+      field: '@key'
+      function: 'IPA111OptionalBooleanFieldsDefaultFalse'
diff --git a/tools/spectral/ipa/rulesets/README.md b/tools/spectral/ipa/rulesets/README.md
index 3053dea3fb..64de5a8d9e 100644
--- a/tools/spectral/ipa/rulesets/README.md
+++ b/tools/spectral/ipa/rulesets/README.md
@@ -776,6 +776,45 @@ Rule checks for the following conditions:
 
 
 
+### IPA-111
+
+Rules are based on [https://mongodb.github.io/ipa/111](https://mongodb.github.io/ipa/111).
+
+#### xgen-IPA-111-optional-fields-no-default
+
+ ![error](https://img.shields.io/badge/error-red) 
+Optional fields must not define a default value.
+
+##### Implementation details
+Rule checks for the following conditions:
+  - Applies to optional (non-required) schema properties in components, request bodies and responses
+  - Boolean fields are exempt (covered by xgen-IPA-111-optional-boolean-fields-default-false)
+  - Fields marked with the x-xgen-server-computed-when-client-omitted extension are exempt
+  - Fails if the field defines a default value
+
+#### xgen-IPA-111-effective-fields-read-only
+
+ ![error](https://img.shields.io/badge/error-red) 
+Effective-value fields must be marked as readOnly: true and must not appear in request schemas.
+
+##### Implementation details
+Rule checks for the following conditions:
+  - Applies to schema properties whose name starts with the "effective" prefix
+  - Fails if the field appears in a request schema
+  - Fails if the field is not marked with readOnly: true
+
+#### xgen-IPA-111-optional-boolean-fields-default-false
+
+ ![error](https://img.shields.io/badge/error-red) 
+Optional boolean fields must default to false.
+
+##### Implementation details
+Rule checks for the following conditions:
+  - Applies to optional (non-required) boolean schema properties in components, request bodies and responses
+  - Fails if the field does not define a default value of false
+
+
+
 ### IPA-112
 
 Rules are based on [https://mongodb.github.io/ipa/112](https://mongodb.github.io/ipa/112).
diff --git a/tools/spectral/ipa/rulesets/functions/IPA111EffectiveFieldsReadOnly.js b/tools/spectral/ipa/rulesets/functions/IPA111EffectiveFieldsReadOnly.js
new file mode 100644
index 0000000000..365b9283c5
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/functions/IPA111EffectiveFieldsReadOnly.js
@@ -0,0 +1,41 @@
+import { evaluateAndCollectAdoptionStatus, handleInternalError } from './utils/collectionUtils.js';
+import { pathIsForRequestVersion, resolveObject } from './utils/componentUtils.js';
+
+const EFFECTIVE_PREFIX_REGEX = /^effective[A-Z]/;
+const REQUEST_ERROR_MESSAGE =
+  'Effective-value fields represent server-computed state and must not appear in request schemas.';
+const READ_ONLY_ERROR_MESSAGE = 'Effective-value fields must be marked as readOnly: true.';
+
+export default (input, _, { path, documentInventory, rule }) => {
+  const ruleName = rule.name;
+  const oas = documentInventory.unresolved;
+  const property = resolveObject(oas, path);
+
+  // Skip schema references ($ref):
+  // Referenced schemas are validated separately to prevent duplicate violations
+  if (!property) {
+    return;
+  }
+
+  // The rule only applies to effective-value fields, identified by the "effective" prefix
+  if (!EFFECTIVE_PREFIX_REGEX.test(input)) {
+    return;
+  }
+
+  const errors = checkViolationsAndReturnErrors(property, path, ruleName);
+  return evaluateAndCollectAdoptionStatus(errors, ruleName, property, path);
+};
+
+function checkViolationsAndReturnErrors(property, path, ruleName) {
+  try {
+    if (pathIsForRequestVersion(path)) {
+      return [{ path, message: REQUEST_ERROR_MESSAGE }];
+    }
+    if (property.readOnly !== true) {
+      return [{ path, message: READ_ONLY_ERROR_MESSAGE }];
+    }
+    return [];
+  } catch (e) {
+    return handleInternalError(ruleName, path, e);
+  }
+}
diff --git a/tools/spectral/ipa/rulesets/functions/IPA111OptionalBooleanFieldsDefaultFalse.js b/tools/spectral/ipa/rulesets/functions/IPA111OptionalBooleanFieldsDefaultFalse.js
new file mode 100644
index 0000000000..b694c63cad
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/functions/IPA111OptionalBooleanFieldsDefaultFalse.js
@@ -0,0 +1,36 @@
+import { evaluateAndCollectAdoptionStatus, handleInternalError } from './utils/collectionUtils.js';
+import { resolveObject } from './utils/componentUtils.js';
+import { isRequiredProperty } from './utils/schemaUtils.js';
+
+const ERROR_MESSAGE = 'Optional boolean fields must default to false.';
+
+export default (input, _, { path, documentInventory, rule }) => {
+  const ruleName = rule.name;
+  const oas = documentInventory.unresolved;
+  const property = resolveObject(oas, path);
+
+  // Skip schema references ($ref) and non-boolean fields:
+  // Referenced schemas are validated separately to prevent duplicate violations
+  if (!property || property.type !== 'boolean') {
+    return;
+  }
+
+  // The rule only applies to optional fields
+  if (isRequiredProperty(oas, path)) {
+    return;
+  }
+
+  const errors = checkViolationsAndReturnErrors(property, path, ruleName);
+  return evaluateAndCollectAdoptionStatus(errors, ruleName, property, path);
+};
+
+function checkViolationsAndReturnErrors(property, path, ruleName) {
+  try {
+    if (property.default !== false) {
+      return [{ path, message: ERROR_MESSAGE }];
+    }
+    return [];
+  } catch (e) {
+    return handleInternalError(ruleName, path, e);
+  }
+}
diff --git a/tools/spectral/ipa/rulesets/functions/IPA111OptionalFieldsNoDefault.js b/tools/spectral/ipa/rulesets/functions/IPA111OptionalFieldsNoDefault.js
new file mode 100644
index 0000000000..85c97a7e8f
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/functions/IPA111OptionalFieldsNoDefault.js
@@ -0,0 +1,48 @@
+import { evaluateAndCollectAdoptionStatus, handleInternalError } from './utils/collectionUtils.js';
+import { resolveObject } from './utils/componentUtils.js';
+import { isRequiredProperty } from './utils/schemaUtils.js';
+import { hasServerComputedWhenClientOmittedExtension } from './utils/extensions.js';
+
+const ERROR_MESSAGE =
+  'Optional fields must not define a default value. Remove the default or mark the field with x-xgen-server-computed-when-client-omitted if the server computes it when omitted.';
+
+export default (input, _, { path, documentInventory, rule }) => {
+  const ruleName = rule.name;
+  const oas = documentInventory.unresolved;
+  const property = resolveObject(oas, path);
+
+  // Skip schema references ($ref):
+  // Referenced schemas are validated separately to prevent duplicate violations
+  if (!property) {
+    return;
+  }
+
+  // Boolean fields are handled by xgen-IPA-111-optional-boolean-fields-default-false
+  if (property.type === 'boolean') {
+    return;
+  }
+
+  // The rule only applies to optional fields
+  if (isRequiredProperty(oas, path)) {
+    return;
+  }
+
+  // Fields computed by the server when the client omits them are allowed to define a default
+  if (hasServerComputedWhenClientOmittedExtension(property)) {
+    return;
+  }
+
+  const errors = checkViolationsAndReturnErrors(property, path, ruleName);
+  return evaluateAndCollectAdoptionStatus(errors, ruleName, property, path);
+};
+
+function checkViolationsAndReturnErrors(property, path, ruleName) {
+  try {
+    if (property.default !== undefined) {
+      return [{ path, message: ERROR_MESSAGE }];
+    }
+    return [];
+  } catch (e) {
+    return handleInternalError(ruleName, path, e);
+  }
+}
diff --git a/tools/spectral/ipa/rulesets/functions/utils/extensions.js b/tools/spectral/ipa/rulesets/functions/utils/extensions.js
index 29cc488496..c7f551d450 100644
--- a/tools/spectral/ipa/rulesets/functions/utils/extensions.js
+++ b/tools/spectral/ipa/rulesets/functions/utils/extensions.js
@@ -1,5 +1,17 @@
 export const VERB_OVERRIDE_EXTENSION = 'x-xgen-method-verb-override';
 export const OPERATION_ID_OVERRIDE_EXTENSION = 'x-xgen-operation-id-override';
+export const SERVER_COMPUTED_WHEN_CLIENT_OMITTED_EXTENSION = 'x-xgen-server-computed-when-client-omitted';
+
+/**
+ * Checks if the object has the extension "x-xgen-server-computed-when-client-omitted", marking a field
+ * whose value is computed by the server when the client omits it.
+ *
+ * @param object the object to evaluate
+ * @returns {boolean} true if the object has the extension, otherwise false
+ */
+export function hasServerComputedWhenClientOmittedExtension(object) {
+  return Object.keys(object).includes(SERVER_COMPUTED_WHEN_CLIENT_OMITTED_EXTENSION);
+}
 
 /**
  * Checks if the object has an extension "x-xgen-method-verb-override" with the customMethod boolean set to true
diff --git a/tools/spectral/ipa/rulesets/functions/utils/schemaUtils.js b/tools/spectral/ipa/rulesets/functions/utils/schemaUtils.js
index 5dfd8d0991..6ec0d09ffc 100644
--- a/tools/spectral/ipa/rulesets/functions/utils/schemaUtils.js
+++ b/tools/spectral/ipa/rulesets/functions/utils/schemaUtils.js
@@ -1,3 +1,21 @@
+import { resolveObject } from './componentUtils.js';
+
+/**
+ * Checks if a schema property is listed as required by its parent schema.
+ *
+ * Given the JSON path to a property (ending in `['properties', '<name>']`), this resolves the
+ * enclosing schema object and inspects its `required` array.
+ *
+ * @param {Object} oas the OpenAPI Specification object to resolve against
+ * @param {string[]} propertyPath the JSON path to the property
+ * @returns {boolean} true if the property is listed in the parent schema's `required` array, false otherwise
+ */
+export function isRequiredProperty(oas, propertyPath) {
+  const propertyName = propertyPath[propertyPath.length - 1];
+  const parentSchema = resolveObject(oas, propertyPath.slice(0, propertyPath.length - 2));
+  return Array.isArray(parentSchema?.required) && parentSchema.required.includes(propertyName);
+}
+
 /**
  * Checks if the object has results property
  * @param {Object} schema