diff --git a/x-pack/plugins/cases/common/types/api/case/v1.test.ts b/x-pack/plugins/cases/common/types/api/case/v1.test.ts
index 40c980d633545c4..91676b7ca65105e 100644
--- a/x-pack/plugins/cases/common/types/api/case/v1.test.ts
+++ b/x-pack/plugins/cases/common/types/api/case/v1.test.ts
@@ -5,6 +5,18 @@
  * 2.0.
  */
 
+import {
+  MAX_CATEGORY_FILTER_LENGTH,
+  MAX_TAGS_FILTER_LENGTH,
+  MAX_ASSIGNEES_FILTER_LENGTH,
+  MAX_REPORTERS_FILTER_LENGTH,
+  MAX_ASSIGNEES_PER_CASE,
+  MAX_DESCRIPTION_LENGTH,
+  MAX_TAGS_PER_CASE,
+  MAX_LENGTH_PER_TAG,
+  MAX_TITLE_LENGTH,
+  MAX_CATEGORY_LENGTH,
+} from '../../../constants';
 import { PathReporter } from 'io-ts/lib/PathReporter';
 import { AttachmentType } from '../../domain/attachment/v1';
 import { CaseSeverity, CaseStatuses } from '../../domain/case/v1';
@@ -187,6 +199,66 @@ describe('Status', () => {
         right: defaultRequest,
       });
     });
+
+    it(`throws an error when the assignees are more than ${MAX_ASSIGNEES_PER_CASE}`, async () => {
+      const assignees = Array(MAX_ASSIGNEES_PER_CASE + 1).fill({ uid: 'foobar' });
+
+      expect(
+        PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, assignees }))
+      ).toContain('The length of the field assignees is too long. Array must be of length <= 10.');
+    });
+
+    it('does not throw an error with empty assignees', async () => {
+      expect(
+        PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, assignees: [] }))
+      ).toContain('No errors!');
+    });
+
+    it('does not throw an error with undefined assignees', async () => {
+      const { assignees, ...rest } = defaultRequest;
+
+      expect(PathReporter.report(CasePostRequestRt.decode(rest))).toContain('No errors!');
+    });
+
+    it(`throws an error when the description contains more than ${MAX_DESCRIPTION_LENGTH} characters`, async () => {
+      const description = 'a'.repeat(MAX_DESCRIPTION_LENGTH + 1);
+
+      expect(
+        PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, description }))
+      ).toContain('The length of the description is too long. The maximum length is 30000.');
+    });
+
+    it(`throws an error when there are more than ${MAX_TAGS_PER_CASE} tags`, async () => {
+      const tags = Array(MAX_TAGS_PER_CASE + 1).fill('foobar');
+
+      expect(PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, tags }))).toContain(
+        'The length of the field tags is too long. Array must be of length <= 200.'
+      );
+    });
+
+    it(`throws an error when the a tag is more than ${MAX_LENGTH_PER_TAG} characters`, async () => {
+      const tag = 'a'.repeat(MAX_LENGTH_PER_TAG + 1);
+
+      expect(
+        PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, tags: [tag] }))
+      ).toContain('The length of the tag is too long. The maximum length is 256.');
+    });
+
+    it(`throws an error when the title contains more than ${MAX_TITLE_LENGTH} characters`, async () => {
+      const title = 'a'.repeat(MAX_TITLE_LENGTH + 1);
+
+      expect(PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, title }))).toContain(
+        'The length of the title is too long. The maximum length is 160.'
+      );
+    });
+
+    it(`throws an error when the category contains more than ${MAX_CATEGORY_LENGTH} characters`, async () => {
+      const category = 'a'.repeat(MAX_CATEGORY_LENGTH + 1);
+
+      expect(
+        PathReporter.report(CasePostRequestRt.decode({ ...defaultRequest, category }))
+      ).toContain('The length of the category is too long. The maximum length is 50.');
+    });
   });
 
   describe('CasesFindRequestRt', () => {
@@ -276,6 +348,38 @@ describe('Status', () => {
           'No errors!'
         );
       });
+
+      it(`throws an error when the category array has ${MAX_CATEGORY_FILTER_LENGTH} items`, async () => {
+        const category = Array(MAX_CATEGORY_FILTER_LENGTH + 1).fill('foobar');
+
+        expect(PathReporter.report(CasesFindRequestRt.decode({ category }))).toContain(
+          'The length of the field category is too long. Array must be of length <= 100.'
+        );
+      });
+
+      it(`throws an error when the tags array has ${MAX_TAGS_FILTER_LENGTH} items`, async () => {
+        const tags = Array(MAX_TAGS_FILTER_LENGTH + 1).fill('foobar');
+
+        expect(PathReporter.report(CasesFindRequestRt.decode({ tags }))).toContain(
+          'The length of the field tags is too long. Array must be of length <= 100.'
+        );
+      });
+
+      it(`throws an error when the assignees array has ${MAX_ASSIGNEES_FILTER_LENGTH} items`, async () => {
+        const assignees = Array(MAX_ASSIGNEES_FILTER_LENGTH + 1).fill('foobar');
+
+        expect(PathReporter.report(CasesFindRequestRt.decode({ assignees }))).toContain(
+          'The length of the field assignees is too long. Array must be of length <= 100.'
+        );
+      });
+
+      it(`throws an error when the reporters array has ${MAX_REPORTERS_FILTER_LENGTH} items`, async () => {
+        const reporters = Array(MAX_REPORTERS_FILTER_LENGTH + 1).fill('foobar');
+
+        expect(PathReporter.report(CasesFindRequestRt.decode({ reporters }))).toContain(
+          'The length of the field reporters is too long. Array must be of length <= 100.'
+        );
+      });
     });
   });
 });
@@ -393,6 +497,64 @@ describe('CasePatchRequestRt', () => {
       right: defaultRequest,
     });
   });
+
+  it(`throws an error when the assignees are more than ${MAX_ASSIGNEES_PER_CASE}`, async () => {
+    const assignees = Array(MAX_ASSIGNEES_PER_CASE + 1).fill({ uid: 'foobar' });
+
+    expect(
+      PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, assignees }))
+    ).toContain('The length of the field assignees is too long. Array must be of length <= 10.');
+  });
+
+  it('does not throw an error with empty assignees', async () => {
+    expect(
+      PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, assignees: [] }))
+    ).toContain('No errors!');
+  });
+
+  it('does not throw an error with undefined assignees', async () => {
+    expect(PathReporter.report(CasePatchRequestRt.decode(defaultRequest))).toContain('No errors!');
+  });
+
+  it(`throws an error when the description contains more than ${MAX_DESCRIPTION_LENGTH} characters`, async () => {
+    const description = 'a'.repeat(MAX_DESCRIPTION_LENGTH + 1);
+
+    expect(
+      PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, description }))
+    ).toContain('The length of the description is too long. The maximum length is 30000.');
+  });
+
+  it(`throws an error when there are more than ${MAX_TAGS_PER_CASE} tags`, async () => {
+    const tags = Array(MAX_TAGS_PER_CASE + 1).fill('foobar');
+
+    expect(PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, tags }))).toContain(
+      'The length of the field tags is too long. Array must be of length <= 200.'
+    );
+  });
+
+  it(`throws an error when the a tag is more than ${MAX_LENGTH_PER_TAG} characters`, async () => {
+    const tag = 'a'.repeat(MAX_LENGTH_PER_TAG + 1);
+
+    expect(
+      PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, tags: [tag] }))
+    ).toContain('The length of the tag is too long. The maximum length is 256.');
+  });
+
+  it(`throws an error when the title contains more than ${MAX_TITLE_LENGTH} characters`, async () => {
+    const title = 'a'.repeat(MAX_TITLE_LENGTH + 1);
+
+    expect(PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, title }))).toContain(
+      'The length of the title is too long. The maximum length is 160.'
+    );
+  });
+
+  it(`throws an error when the category contains more than ${MAX_CATEGORY_LENGTH} characters`, async () => {
+    const category = 'a'.repeat(MAX_CATEGORY_LENGTH + 1);
+
+    expect(
+      PathReporter.report(CasePatchRequestRt.decode({ ...defaultRequest, category }))
+    ).toContain('The length of the category is too long. The maximum length is 50.');
+  });
 });
 
 describe('CasesPatchRequestRt', () => {
@@ -423,6 +585,24 @@ describe('CasesPatchRequestRt', () => {
       right: defaultRequest,
     });
   });
+
+  it(`throws an error when the assignees are more than ${MAX_ASSIGNEES_PER_CASE}`, async () => {
+    const assignees = Array(MAX_ASSIGNEES_PER_CASE + 1).fill({ uid: 'foobar' });
+
+    expect(
+      PathReporter.report(
+        CasesPatchRequestRt.decode({
+          cases: [
+            {
+              id: 'basic-case-id',
+              version: 'WzQ3LDFd',
+              assignees,
+            },
+          ],
+        })
+      )
+    ).toContain('The length of the field assignees is too long. Array must be of length <= 10.');
+  });
 });
 
 describe('CasePushRequestParamsRt', () => {
diff --git a/x-pack/plugins/cases/common/types/api/case/v1.ts b/x-pack/plugins/cases/common/types/api/case/v1.ts
index 97981f90fb8dc11..7a92c1f32ca129e 100644
--- a/x-pack/plugins/cases/common/types/api/case/v1.ts
+++ b/x-pack/plugins/cases/common/types/api/case/v1.ts
@@ -19,6 +19,8 @@ import {
   MAX_TAGS_FILTER_LENGTH,
   MAX_CASES_TO_UPDATE,
   MAX_BULK_GET_CASES,
+  MAX_CATEGORY_FILTER_LENGTH,
+  MAX_ASSIGNEES_PER_CASE,
 } from '../../../constants';
 import {
   limitedStringSchema,
@@ -35,7 +37,7 @@ import {
   RelatedCaseRt,
 } from '../../domain/case/v1';
 import { CaseConnectorRt } from '../../domain/connector/v1';
-import { CaseAssigneesRt, UserRt } from '../../domain/user/v1';
+import { CaseUserProfileRt, UserRt } from '../../domain/user/v1';
 import { CasesStatusResponseRt } from '../stats/v1';
 
 /**
@@ -84,7 +86,12 @@ export const CasePostRequestRt = rt.intersection([
       /**
        * The users assigned to the case
        */
-      assignees: CaseAssigneesRt,
+      assignees: limitedArraySchema({
+        codec: CaseUserProfileRt,
+        fieldName: 'assignees',
+        min: 0,
+        max: MAX_ASSIGNEES_PER_CASE,
+      }),
       /**
        * The severity of the case. The severity is
        * default it to "low" if not provided.
@@ -214,7 +221,15 @@ export const CasesFindRequestRt = rt.intersection([
       /**
        * The category of the case.
        */
-      category: rt.union([rt.array(rt.string), rt.string]),
+      category: rt.union([
+        limitedArraySchema({
+          codec: rt.string,
+          fieldName: 'category',
+          min: 0,
+          max: MAX_CATEGORY_FILTER_LENGTH,
+        }),
+        rt.string,
+      ]),
     })
   ),
   paginationSchema({ maxPerPage: MAX_CASES_PER_PAGE }),
@@ -330,7 +345,12 @@ export const CasePatchRequestRt = rt.intersection([
       /**
        * The users assigned to this case
        */
-      assignees: CaseAssigneesRt,
+      assignees: limitedArraySchema({
+        codec: CaseUserProfileRt,
+        fieldName: 'assignees',
+        min: 0,
+        max: MAX_ASSIGNEES_PER_CASE,
+      }),
       /**
        * The category of the case.
        */
diff --git a/x-pack/plugins/cases/server/client/cases/create.test.ts b/x-pack/plugins/cases/server/client/cases/create.test.ts
index 9918cc302c033eb..61672e70d8e3d19 100644
--- a/x-pack/plugins/cases/server/client/cases/create.test.ts
+++ b/x-pack/plugins/cases/server/client/cases/create.test.ts
@@ -10,6 +10,7 @@ import {
   MAX_TAGS_PER_CASE,
   MAX_LENGTH_PER_TAG,
   MAX_TITLE_LENGTH,
+  MAX_ASSIGNEES_PER_CASE,
 } from '../../../common/constants';
 import { SECURITY_SOLUTION_OWNER } from '../../../common';
 import { mockCases } from '../../mocks';
@@ -82,6 +83,14 @@ describe('create', () => {
         theCase: caseSO,
       });
     });
+
+    it('should throw an error if the assignees array length is too long', async () => {
+      const assignees = Array(MAX_ASSIGNEES_PER_CASE + 1).fill({ uid: 'foo' });
+
+      await expect(create({ ...theCase, assignees }, clientArgs)).rejects.toThrow(
+        `Failed to create case: Error: The length of the field assignees is too long. Array must be of length <= ${MAX_ASSIGNEES_PER_CASE}.`
+      );
+    });
   });
 
   describe('Attributes', () => {
diff --git a/x-pack/plugins/cases/server/client/cases/create.ts b/x-pack/plugins/cases/server/client/cases/create.ts
index 9467fe9ecc88759..30524c1db65951c 100644
--- a/x-pack/plugins/cases/server/client/cases/create.ts
+++ b/x-pack/plugins/cases/server/client/cases/create.ts
@@ -12,8 +12,6 @@ import { SavedObjectsUtils } from '@kbn/core/server';
 import type { Case } from '../../../common/types/domain';
 import { CaseSeverity, UserActionTypes, CaseRt } from '../../../common/types/domain';
 import { decodeWithExcessOrThrow } from '../../../common/api';
-import { MAX_ASSIGNEES_PER_CASE } from '../../../common/constants';
-import { areTotalAssigneesInvalid } from '../../../common/utils/validators';
 
 import { Operations } from '../../authorization';
 import { createCaseError } from '../../common/error';
@@ -63,12 +61,6 @@ export const create = async (data: CasePostRequest, clientArgs: CasesClientArgs)
       licensingService.notifyUsage(LICENSING_CASE_ASSIGNMENT_FEATURE);
     }
 
-    if (areTotalAssigneesInvalid(query.assignees)) {
-      throw Boom.badRequest(
-        `You cannot assign more than ${MAX_ASSIGNEES_PER_CASE} assignees to a case.`
-      );
-    }
-
     const newCase = await caseService.postNewCase({
       attributes: transformNewCase({
         user,
diff --git a/x-pack/plugins/cases/server/client/cases/find.test.ts b/x-pack/plugins/cases/server/client/cases/find.test.ts
index 0a09fa8b5b7b277..8acb91b40c383fc 100644
--- a/x-pack/plugins/cases/server/client/cases/find.test.ts
+++ b/x-pack/plugins/cases/server/client/cases/find.test.ts
@@ -128,7 +128,7 @@ describe('find', () => {
       const findRequest = createCasesClientMockFindRequest({ category });
 
       await expect(find(findRequest, clientArgs)).rejects.toThrow(
-        `Error: Too many categories provided. The maximum allowed is ${MAX_CATEGORY_FILTER_LENGTH}`
+        `Error: The length of the field category is too long. Array must be of length <= ${MAX_CATEGORY_FILTER_LENGTH}`
       );
     });
 
diff --git a/x-pack/plugins/cases/server/client/cases/find.ts b/x-pack/plugins/cases/server/client/cases/find.ts
index 9c8699ce9db8481..c61c4ba71ffde4a 100644
--- a/x-pack/plugins/cases/server/client/cases/find.ts
+++ b/x-pack/plugins/cases/server/client/cases/find.ts
@@ -10,7 +10,6 @@ import Boom from '@hapi/boom';
 
 import type { CasesFindRequest, CasesFindResponse } from '../../../common/types/api';
 import { CasesFindRequestRt, CasesFindResponseRt } from '../../../common/types/api';
-import { MAX_CATEGORY_FILTER_LENGTH } from '../../../common/constants';
 import { decodeWithExcessOrThrow } from '../../../common/api';
 
 import { createCaseError } from '../../common/error';
@@ -22,16 +21,6 @@ import { LICENSING_CASE_ASSIGNMENT_FEATURE } from '../../common/constants';
 import type { CasesFindQueryParams } from '../types';
 import { decodeOrThrow } from '../../../common/api/runtime_types';
 
-/**
- * Throws an error if the user tries to filter by more than MAX_CATEGORY_FILTER_LENGTH categories.
- */
-function throwIfCategoryParamTooLong(category?: string[] | string) {
-  if (Array.isArray(category) && category.length > MAX_CATEGORY_FILTER_LENGTH)
-    throw Boom.badRequest(
-      `Too many categories provided. The maximum allowed is ${MAX_CATEGORY_FILTER_LENGTH}`
-    );
-}
-
 /**
  * Retrieves a case and optionally its comments.
  *
@@ -52,8 +41,6 @@ export const find = async (
   try {
     const queryParams = decodeWithExcessOrThrow(CasesFindRequestRt)(params);
 
-    throwIfCategoryParamTooLong(queryParams.category);
-
     /**
      * Assign users to a case is only available to Platinum+
      */
diff --git a/x-pack/plugins/cases/server/client/cases/update.test.ts b/x-pack/plugins/cases/server/client/cases/update.test.ts
index 039f4e858280448..17b51658b12335d 100644
--- a/x-pack/plugins/cases/server/client/cases/update.test.ts
+++ b/x-pack/plugins/cases/server/client/cases/update.test.ts
@@ -13,6 +13,7 @@ import {
   MAX_TITLE_LENGTH,
   MAX_CASES_TO_UPDATE,
   MAX_USER_ACTIONS_PER_CASE,
+  MAX_ASSIGNEES_PER_CASE,
 } from '../../../common/constants';
 import { mockCases } from '../../mocks';
 import { createCasesClientMockArgs } from '../mocks';
@@ -279,6 +280,27 @@ describe('update', () => {
         `"Failed to update case, ids: [{\\"id\\":\\"mock-id-1\\",\\"version\\":\\"WzAsMV0=\\"}]: Error: invalid keys \\"foo\\""`
       );
     });
+
+    it('should throw an error if the assignees array length is too long', async () => {
+      const assignees = Array(MAX_ASSIGNEES_PER_CASE + 1).fill({ uid: 'foo' });
+
+      await expect(
+        update(
+          {
+            cases: [
+              {
+                id: mockCases[0].id,
+                version: mockCases[0].version ?? '',
+                assignees,
+              },
+            ],
+          },
+          clientArgs
+        )
+      ).rejects.toThrow(
+        'Failed to update case, ids: [{"id":"mock-id-1","version":"WzAsMV0="}]: Error: The length of the field assignees is too long. Array must be of length <= 10.'
+      );
+    });
   });
 
   describe('Category', () => {
diff --git a/x-pack/plugins/cases/server/client/cases/update.ts b/x-pack/plugins/cases/server/client/cases/update.ts
index 1844b12b3ab07e1..121fd2a8e3aa5cd 100644
--- a/x-pack/plugins/cases/server/client/cases/update.ts
+++ b/x-pack/plugins/cases/server/client/cases/update.ts
@@ -25,11 +25,9 @@ import type { PatchCasesArgs } from '../../services/cases/types';
 import type { UserActionEvent, UserActionsDict } from '../../services/user_actions/types';
 
 import type { CasePatchRequest, CasesPatchRequest } from '../../../common/types/api';
-import { areTotalAssigneesInvalid } from '../../../common/utils/validators';
 import {
   CASE_COMMENT_SAVED_OBJECT,
   CASE_SAVED_OBJECT,
-  MAX_ASSIGNEES_PER_CASE,
   MAX_USER_ACTIONS_PER_CASE,
 } from '../../../common/constants';
 import { Operations } from '../../authorization';
@@ -138,27 +136,6 @@ function notifyPlatinumUsage(
   }
 }
 
-/**
- * Throws an error if any of the requests attempt to add more than
- * MAX_ASSIGNEES_PER_CASE to a case
- */
-function throwIfTotalAssigneesAreInvalid(requests: UpdateRequestWithOriginalCase[]) {
-  const requestsUpdatingAssignees = requests.filter(
-    ({ updateReq }) => updateReq.assignees !== undefined
-  );
-
-  if (
-    requestsUpdatingAssignees.some(({ updateReq }) => areTotalAssigneesInvalid(updateReq.assignees))
-  ) {
-    const ids = requestsUpdatingAssignees.map(({ updateReq }) => updateReq.id);
-    throw Boom.badRequest(
-      `You cannot assign more than ${MAX_ASSIGNEES_PER_CASE} assignees to a case, ids: [${ids.join(
-        ', '
-      )}]`
-    );
-  }
-}
-
 /**
  * Get the id from a reference in a comment for a specific type.
  */
@@ -394,7 +371,6 @@ export const update = async (
 
     throwIfUpdateOwner(casesToUpdate);
     throwIfUpdateAssigneesWithoutValidLicense(casesToUpdate, hasPlatinumLicense);
-    throwIfTotalAssigneesAreInvalid(casesToUpdate);
 
     const patchCasesPayload = createPatchCasesPayload({ user, casesToUpdate });
     const userActionsDict = userActionService.creator.buildUserActions({
diff --git a/x-pack/plugins/cases/server/routes/api/comments/find_comments.ts b/x-pack/plugins/cases/server/routes/api/comments/find_comments.ts
index 7d0ba2af2a06135..05e4662f272924c 100644
--- a/x-pack/plugins/cases/server/routes/api/comments/find_comments.ts
+++ b/x-pack/plugins/cases/server/routes/api/comments/find_comments.ts
@@ -7,8 +7,7 @@
 
 import { schema } from '@kbn/config-schema';
 
-import { FindAttachmentsQueryParamsRt } from '../../../../common/types/api';
-import { decodeWithExcessOrThrow } from '../../../../common/api';
+import type { attachmentApiV1 } from '../../../../common/types/api';
 import { CASE_FIND_ATTACHMENTS_URL } from '../../../../common/constants';
 import { createCasesRoute } from '../create_cases_route';
 import { createCaseError } from '../../../common/error';
@@ -23,15 +22,17 @@ export const findCommentsRoute = createCasesRoute({
   },
   handler: async ({ context, request, response }) => {
     try {
-      const query = decodeWithExcessOrThrow(FindAttachmentsQueryParamsRt)(request.query);
-
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
+      const query = request.query as attachmentApiV1.FindAttachmentsQueryParams;
+
+      const res: attachmentApiV1.AttachmentsFindResponse = await client.attachments.find({
+        caseID: request.params.case_id,
+        findQueryParams: query,
+      });
+
       return response.ok({
-        body: await client.attachments.find({
-          caseID: request.params.case_id,
-          findQueryParams: query,
-        }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/comments/get_all_comment.ts b/x-pack/plugins/cases/server/routes/api/comments/get_all_comment.ts
index 72b8f7e6ac98b76..fffb23921e2d346 100644
--- a/x-pack/plugins/cases/server/routes/api/comments/get_all_comment.ts
+++ b/x-pack/plugins/cases/server/routes/api/comments/get_all_comment.ts
@@ -10,6 +10,7 @@ import { schema } from '@kbn/config-schema';
 import { CASE_COMMENTS_URL } from '../../../../common/constants';
 import { createCaseError } from '../../../common/error';
 import { createCasesRoute } from '../create_cases_route';
+import type { attachmentDomainV1 } from '../../../../common/types/domain';
 
 /**
  * @deprecated since version 8.1.0
@@ -27,11 +28,12 @@ export const getAllCommentsRoute = createCasesRoute({
     try {
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
+      const res: attachmentDomainV1.Attachments = await client.attachments.getAll({
+        caseID: request.params.case_id,
+      });
 
       return response.ok({
-        body: await client.attachments.getAll({
-          caseID: request.params.case_id,
-        }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/comments/get_comment.ts b/x-pack/plugins/cases/server/routes/api/comments/get_comment.ts
index 2a863f3ee4df4f0..6267895f587ce2f 100644
--- a/x-pack/plugins/cases/server/routes/api/comments/get_comment.ts
+++ b/x-pack/plugins/cases/server/routes/api/comments/get_comment.ts
@@ -10,6 +10,7 @@ import { schema } from '@kbn/config-schema';
 import { CASE_COMMENT_DETAILS_URL } from '../../../../common/constants';
 import { createCaseError } from '../../../common/error';
 import { createCasesRoute } from '../create_cases_route';
+import type { attachmentDomainV1 } from '../../../../common/types/domain';
 
 export const getCommentRoute = createCasesRoute({
   method: 'get',
@@ -24,12 +25,13 @@ export const getCommentRoute = createCasesRoute({
     try {
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
+      const res: attachmentDomainV1.Attachment = await client.attachments.get({
+        attachmentID: request.params.comment_id,
+        caseID: request.params.case_id,
+      });
 
       return response.ok({
-        body: await client.attachments.get({
-          attachmentID: request.params.comment_id,
-          caseID: request.params.case_id,
-        }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/comments/patch_comment.ts b/x-pack/plugins/cases/server/routes/api/comments/patch_comment.ts
index 8130808e51dcb14..99a697cb0bc9a7c 100644
--- a/x-pack/plugins/cases/server/routes/api/comments/patch_comment.ts
+++ b/x-pack/plugins/cases/server/routes/api/comments/patch_comment.ts
@@ -11,6 +11,7 @@ import { decodeWithExcessOrThrow } from '../../../../common/api';
 import { CASE_COMMENTS_URL } from '../../../../common/constants';
 import { createCaseError } from '../../../common/error';
 import { createCasesRoute } from '../create_cases_route';
+import type { caseDomainV1 } from '../../../../common/types/domain';
 
 export const patchCommentRoute = createCasesRoute({
   method: 'patch',
@@ -26,12 +27,13 @@ export const patchCommentRoute = createCasesRoute({
 
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
+      const res: caseDomainV1.Case = await client.attachments.update({
+        caseID: request.params.case_id,
+        updateRequest: query,
+      });
 
       return response.ok({
-        body: await client.attachments.update({
-          caseID: request.params.case_id,
-          updateRequest: query,
-        }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/comments/post_comment.ts b/x-pack/plugins/cases/server/routes/api/comments/post_comment.ts
index 80ce9386252d710..d4d8f4f4f8db2bb 100644
--- a/x-pack/plugins/cases/server/routes/api/comments/post_comment.ts
+++ b/x-pack/plugins/cases/server/routes/api/comments/post_comment.ts
@@ -7,9 +7,10 @@
 
 import { schema } from '@kbn/config-schema';
 import { CASE_COMMENTS_URL } from '../../../../common/constants';
-import type { AttachmentRequest } from '../../../../common/types/api';
 import { createCaseError } from '../../../common/error';
 import { createCasesRoute } from '../create_cases_route';
+import type { caseDomainV1 } from '../../../../common/types/domain';
+import type { attachmentApiV1 } from '../../../../common/types/api';
 
 export const postCommentRoute = createCasesRoute({
   method: 'post',
@@ -24,10 +25,11 @@ export const postCommentRoute = createCasesRoute({
       const caseContext = await context.cases;
       const casesClient = await caseContext.getCasesClient();
       const caseId = request.params.case_id;
-      const comment = request.body as AttachmentRequest;
+      const comment = request.body as attachmentApiV1.AttachmentRequest;
+      const res: caseDomainV1.Case = await casesClient.attachments.add({ caseId, comment });
 
       return response.ok({
-        body: await casesClient.attachments.add({ caseId, comment }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/internal/bulk_create_attachments.ts b/x-pack/plugins/cases/server/routes/api/internal/bulk_create_attachments.ts
index e0abb28a58efe10..8074d8e626ea7cd 100644
--- a/x-pack/plugins/cases/server/routes/api/internal/bulk_create_attachments.ts
+++ b/x-pack/plugins/cases/server/routes/api/internal/bulk_create_attachments.ts
@@ -6,11 +6,12 @@
  */
 
 import { schema } from '@kbn/config-schema';
-import type { BulkCreateAttachmentsRequest } from '../../../../common/types/api';
 import { INTERNAL_BULK_CREATE_ATTACHMENTS_URL } from '../../../../common/constants';
 import { createCaseError } from '../../../common/error';
 import { createCasesRoute } from '../create_cases_route';
 import { escapeHatch } from '../utils';
+import type { attachmentApiV1 } from '../../../../common/types/api';
+import type { caseDomainV1 } from '../../../../common/types/domain';
 
 export const bulkCreateAttachmentsRoute = createCasesRoute({
   method: 'post',
@@ -26,10 +27,14 @@ export const bulkCreateAttachmentsRoute = createCasesRoute({
       const casesContext = await context.cases;
       const casesClient = await casesContext.getCasesClient();
       const caseId = request.params.case_id;
-      const attachments = request.body as BulkCreateAttachmentsRequest;
+      const attachments = request.body as attachmentApiV1.BulkCreateAttachmentsRequest;
+      const res: caseDomainV1.Case = await casesClient.attachments.bulkCreate({
+        caseId,
+        attachments,
+      });
 
       return response.ok({
-        body: await casesClient.attachments.bulkCreate({ caseId, attachments }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({
diff --git a/x-pack/plugins/cases/server/routes/api/internal/bulk_delete_file_attachments.ts b/x-pack/plugins/cases/server/routes/api/internal/bulk_delete_file_attachments.ts
index c719d16e7ab16f6..d1e62f13c633b40 100644
--- a/x-pack/plugins/cases/server/routes/api/internal/bulk_delete_file_attachments.ts
+++ b/x-pack/plugins/cases/server/routes/api/internal/bulk_delete_file_attachments.ts
@@ -7,12 +7,13 @@
 
 import { schema } from '@kbn/config-schema';
 
-import { BulkDeleteFileAttachmentsRequestRt } from '../../../../common/types/api';
+import { decodeWithExcessOrThrow } from '../../../../common/api';
 import { INTERNAL_DELETE_FILE_ATTACHMENTS_URL } from '../../../../common/constants';
 import { createCasesRoute } from '../create_cases_route';
 import { createCaseError } from '../../../common/error';
 import { escapeHatch } from '../utils';
-import { decodeWithExcessOrThrow } from '../../../../common/api';
+import type { attachmentApiV1 } from '../../../../common/types/api';
+import { BulkDeleteFileAttachmentsRequestRt } from '../../../../common/types/api/attachment/v1';
 
 export const bulkDeleteFileAttachments = createCasesRoute({
   method: 'post',
@@ -27,8 +28,9 @@ export const bulkDeleteFileAttachments = createCasesRoute({
     try {
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
-
-      const requestBody = decodeWithExcessOrThrow(BulkDeleteFileAttachmentsRequestRt)(request.body);
+      const requestBody: attachmentApiV1.BulkDeleteFileAttachmentsRequest = decodeWithExcessOrThrow(
+        BulkDeleteFileAttachmentsRequestRt
+      )(request.body);
 
       await client.attachments.bulkDeleteFileAttachments({
         caseId: request.params.case_id,
diff --git a/x-pack/plugins/cases/server/routes/api/internal/bulk_get_attachments.ts b/x-pack/plugins/cases/server/routes/api/internal/bulk_get_attachments.ts
index 1e59df016e8c6d3..a5cb22f536caa43 100644
--- a/x-pack/plugins/cases/server/routes/api/internal/bulk_get_attachments.ts
+++ b/x-pack/plugins/cases/server/routes/api/internal/bulk_get_attachments.ts
@@ -6,8 +6,9 @@
  */
 
 import { schema } from '@kbn/config-schema';
-import { BulkGetAttachmentsRequestRt } from '../../../../common/types/api';
+import { BulkGetAttachmentsRequestRt } from '../../../../common/types/api/attachment/v1';
 import { decodeWithExcessOrThrow } from '../../../../common/api';
+import type { attachmentApiV1 } from '../../../../common/types/api';
 
 import { INTERNAL_BULK_GET_ATTACHMENTS_URL } from '../../../../common/constants';
 import { createCaseError } from '../../../common/error';
@@ -28,13 +29,17 @@ export const bulkGetAttachmentsRoute = createCasesRoute({
       const caseContext = await context.cases;
       const client = await caseContext.getCasesClient();
 
-      const requestBody = decodeWithExcessOrThrow(BulkGetAttachmentsRequestRt)(request.body);
+      const requestBody: attachmentApiV1.BulkGetAttachmentsRequest = decodeWithExcessOrThrow(
+        BulkGetAttachmentsRequestRt
+      )(request.body);
+
+      const res: attachmentApiV1.BulkGetAttachmentsResponse = await client.attachments.bulkGet({
+        caseID: request.params.case_id,
+        attachmentIDs: requestBody.ids,
+      });
 
       return response.ok({
-        body: await client.attachments.bulkGet({
-          caseID: request.params.case_id,
-          attachmentIDs: requestBody.ids,
-        }),
+        body: res,
       });
     } catch (error) {
       throw createCaseError({