diff --git a/x-pack/plugins/cases/common/api/cases/case.ts b/x-pack/plugins/cases/common/api/cases/case.ts
index 61c31e9cff515..acfca22e70498 100644
--- a/x-pack/plugins/cases/common/api/cases/case.ts
+++ b/x-pack/plugins/cases/common/api/cases/case.ts
@@ -213,7 +213,7 @@ export const CasesFindRequestRt = rt.exact(
     /**
      * Tags to filter by
      */
-    tags: rt.union([limitedArraySchema(rt.string, 0, MAX_TAGS_FILTER_LENGTH), rt.string]),
+    tags: rt.union([limitedArraySchema(rt.string, 0, MAX_TAGS_FILTER_LENGTH, 'tags'), rt.string]),
     /**
      * The status of the case (open, closed, in-progress)
      */
@@ -225,11 +225,17 @@ export const CasesFindRequestRt = rt.exact(
     /**
      * The uids of the user profiles to filter by
      */
-    assignees: rt.union([limitedArraySchema(rt.string, 0, MAX_ASSIGNEES_FILTER_LENGTH), rt.string]),
+    assignees: rt.union([
+      limitedArraySchema(rt.string, 0, MAX_ASSIGNEES_FILTER_LENGTH, 'assignees'),
+      rt.string,
+    ]),
     /**
      * The reporters to filter by
      */
-    reporters: rt.union([limitedArraySchema(rt.string, 0, MAX_REPORTERS_FILTER_LENGTH), rt.string]),
+    reporters: rt.union([
+      limitedArraySchema(rt.string, 0, MAX_REPORTERS_FILTER_LENGTH, 'reporters'),
+      rt.string,
+    ]),
     /**
      * Operator to use for the `search` field
      */
diff --git a/x-pack/plugins/cases/docs/openapi/bundled.json b/x-pack/plugins/cases/docs/openapi/bundled.json
index a367593d6b89e..2ccef20d760a1 100644
--- a/x-pack/plugins/cases/docs/openapi/bundled.json
+++ b/x-pack/plugins/cases/docs/openapi/bundled.json
@@ -232,7 +232,7 @@
                   "items": {
                     "type": "string"
                   },
-                  "maximum": 100
+                  "maxItems": 100
                 }
               ]
             }
@@ -298,7 +298,7 @@
                   "items": {
                     "type": "string"
                   },
-                  "maximum": 100
+                  "maxItems": 100
                 }
               ]
             },
@@ -378,7 +378,7 @@
                   "items": {
                     "type": "string"
                   },
-                  "maximum": 100
+                  "maxItems": 100
                 }
               ]
             },
diff --git a/x-pack/plugins/cases/docs/openapi/bundled.yaml b/x-pack/plugins/cases/docs/openapi/bundled.yaml
index dfb37c895902d..30ca1177c1390 100644
--- a/x-pack/plugins/cases/docs/openapi/bundled.yaml
+++ b/x-pack/plugins/cases/docs/openapi/bundled.yaml
@@ -141,7 +141,7 @@ paths:
               - type: array
                 items:
                   type: string
-                maximum: 100
+                maxItems: 100
         - name: category
           in: query
           description: Filters the returned cases by category. Limited to 100 categories.
@@ -178,7 +178,7 @@ paths:
               - type: array
                 items:
                   type: string
-                maximum: 100
+                maxItems: 100
           example: elastic
         - name: search
           in: query
@@ -225,7 +225,7 @@ paths:
               - type: array
                 items:
                   type: string
-                maximum: 100
+                maxItems: 100
           example: tag-1
         - name: to
           in: query
diff --git a/x-pack/plugins/cases/docs/openapi/paths/s@{spaceid}@api@cases@_find.yaml b/x-pack/plugins/cases/docs/openapi/paths/s@{spaceid}@api@cases@_find.yaml
index 09c28446def69..d02399d081f33 100644
--- a/x-pack/plugins/cases/docs/openapi/paths/s@{spaceid}@api@cases@_find.yaml
+++ b/x-pack/plugins/cases/docs/openapi/paths/s@{spaceid}@api@cases@_find.yaml
@@ -20,7 +20,7 @@ get:
           - type: array
             items:
               type: string
-            maximum: 100
+            maxItems: 100
     - name: category
       in: query
       description: Filters the returned cases by category. Limited to 100 categories.
@@ -62,7 +62,7 @@ get:
           - type: array
             items:
               type: string
-            maximum: 100
+            maxItems: 100
       example: elastic
     - name: search
       in: query
@@ -109,7 +109,7 @@ get:
           - type: array
             items:
               type: string
-            maximum: 100
+            maxItems: 100
       example: tag-1
     - name: to
       in: query
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 76e15425ecef5..b7d9d9117ad7e 100644
--- a/x-pack/plugins/cases/server/client/cases/find.test.ts
+++ b/x-pack/plugins/cases/server/client/cases/find.test.ts
@@ -126,7 +126,7 @@ describe('find', () => {
       const findRequest = createCasesClientMockFindRequest({ tags });
 
       await expect(find(findRequest, clientArgs)).rejects.toThrowError(
-        'Error: array must be of length <= 100'
+        `Error: The length of the field tags is too long. Array must be of length <= ${MAX_TAGS_FILTER_LENGTH}`
       );
     });
 
@@ -136,7 +136,7 @@ describe('find', () => {
       const findRequest = createCasesClientMockFindRequest({ assignees });
 
       await expect(find(findRequest, clientArgs)).rejects.toThrowError(
-        'Error: array must be of length <= 100'
+        `Error: The length of the field assignees is too long. Array must be of length <= ${MAX_ASSIGNEES_FILTER_LENGTH}`
       );
     });
 
@@ -146,7 +146,7 @@ describe('find', () => {
       const findRequest = createCasesClientMockFindRequest({ reporters });
 
       await expect(find(findRequest, clientArgs)).rejects.toThrowError(
-        'Error: array must be of length <= 100'
+        `Error: The length of the field reporters is too long. Array must be of length <= ${MAX_REPORTERS_FILTER_LENGTH}.`
       );
     });
   });