diff --git a/output/openapi/elasticsearch-openapi.json b/output/openapi/elasticsearch-openapi.json
index 116ce5e278..a67139cc14 100644
--- a/output/openapi/elasticsearch-openapi.json
+++ b/output/openapi/elasticsearch-openapi.json
@@ -56016,10 +56016,17 @@
                 "type": "boolean"
               },
               "keywords": {
-                "type": "array",
-                "items": {
-                  "type": "string"
-                }
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "string"
+                    }
+                  }
+                ]
               },
               "keywords_path": {
                 "type": "string"
@@ -57498,8 +57505,7 @@
               }
             },
             "required": [
-              "type",
-              "buffer_size"
+              "type"
             ]
           }
         ]
diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index 71ae0df83d..9d5a196ada 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -37792,10 +37792,17 @@
                 "type": "boolean"
               },
               "keywords": {
-                "type": "array",
-                "items": {
-                  "type": "string"
-                }
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "string"
+                    }
+                  }
+                ]
               },
               "keywords_path": {
                 "type": "string"
@@ -39274,8 +39281,7 @@
               }
             },
             "required": [
-              "type",
-              "buffer_size"
+              "type"
             ]
           }
         ]
diff --git a/output/schema/schema-serverless.json b/output/schema/schema-serverless.json
index 03e93b61bc..b957cf4f51 100644
--- a/output/schema/schema-serverless.json
+++ b/output/schema/schema-serverless.json
@@ -82270,14 +82270,26 @@
           "name": "keywords",
           "required": false,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "string",
-                "namespace": "_builtins"
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "string",
+                  "namespace": "_builtins"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "string",
+                    "namespace": "_builtins"
+                  }
+                }
               }
-            }
+            ],
+            "kind": "union_of"
           }
         },
         {
@@ -84417,7 +84429,7 @@
         "name": "Tokenizer",
         "namespace": "_types.analysis"
       },
-      "specLocation": "_types/analysis/tokenizers.ts#L137-L139",
+      "specLocation": "_types/analysis/tokenizers.ts#L140-L142",
       "type": {
         "items": [
           {
@@ -84444,7 +84456,7 @@
         "name": "TokenizerDefinition",
         "namespace": "_types.analysis"
       },
-      "specLocation": "_types/analysis/tokenizers.ts#L141-L164",
+      "specLocation": "_types/analysis/tokenizers.ts#L144-L167",
       "type": {
         "items": [
           {
@@ -84782,7 +84794,8 @@
         },
         {
           "name": "buffer_size",
-          "required": true,
+          "required": false,
+          "serverDefault": 256,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -84792,7 +84805,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L68-L71"
+      "specLocation": "_types/analysis/tokenizers.ts#L68-L74"
     },
     {
       "inherits": {
@@ -84816,7 +84829,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L73-L75"
+      "specLocation": "_types/analysis/tokenizers.ts#L76-L78"
     },
     {
       "inherits": {
@@ -84840,7 +84853,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L77-L79"
+      "specLocation": "_types/analysis/tokenizers.ts#L80-L82"
     },
     {
       "inherits": {
@@ -84912,7 +84925,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L81-L90"
+      "specLocation": "_types/analysis/tokenizers.ts#L84-L93"
     },
     {
       "inherits": {
@@ -85018,7 +85031,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L92-L99"
+      "specLocation": "_types/analysis/tokenizers.ts#L95-L102"
     },
     {
       "inherits": {
@@ -85075,7 +85088,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L101-L106"
+      "specLocation": "_types/analysis/tokenizers.ts#L104-L109"
     },
     {
       "inherits": {
@@ -85110,7 +85123,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L108-L111"
+      "specLocation": "_types/analysis/tokenizers.ts#L111-L114"
     },
     {
       "inherits": {
@@ -85145,7 +85158,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L113-L116"
+      "specLocation": "_types/analysis/tokenizers.ts#L116-L119"
     },
     {
       "inherits": {
@@ -85180,7 +85193,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L118-L121"
+      "specLocation": "_types/analysis/tokenizers.ts#L121-L124"
     },
     {
       "inherits": {
@@ -85204,7 +85217,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L123-L125"
+      "specLocation": "_types/analysis/tokenizers.ts#L126-L128"
     },
     {
       "inherits": {
@@ -85239,7 +85252,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L127-L130"
+      "specLocation": "_types/analysis/tokenizers.ts#L130-L133"
     },
     {
       "inherits": {
@@ -85274,7 +85287,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L132-L135"
+      "specLocation": "_types/analysis/tokenizers.ts#L135-L138"
     },
     {
       "inherits": {
diff --git a/output/schema/schema.json b/output/schema/schema.json
index 8734cfb794..b3ec235486 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -67049,14 +67049,26 @@
           "name": "keywords",
           "required": false,
           "type": {
-            "kind": "array_of",
-            "value": {
-              "kind": "instance_of",
-              "type": {
-                "name": "string",
-                "namespace": "_builtins"
+            "kind": "union_of",
+            "items": [
+              {
+                "kind": "instance_of",
+                "type": {
+                  "name": "string",
+                  "namespace": "_builtins"
+                }
+              },
+              {
+                "kind": "array_of",
+                "value": {
+                  "kind": "instance_of",
+                  "type": {
+                    "name": "string",
+                    "namespace": "_builtins"
+                  }
+                }
               }
-            }
+            ]
           }
         },
         {
@@ -67107,7 +67119,8 @@
         },
         {
           "name": "buffer_size",
-          "required": true,
+          "required": false,
+          "serverDefault": 256,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -67117,7 +67130,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L68-L71"
+      "specLocation": "_types/analysis/tokenizers.ts#L68-L74"
     },
     {
       "kind": "interface",
@@ -67746,7 +67759,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L73-L75"
+      "specLocation": "_types/analysis/tokenizers.ts#L76-L78"
     },
     {
       "kind": "interface",
@@ -67932,7 +67945,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L77-L79"
+      "specLocation": "_types/analysis/tokenizers.ts#L80-L82"
     },
     {
       "kind": "interface",
@@ -68177,7 +68190,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L81-L90"
+      "specLocation": "_types/analysis/tokenizers.ts#L84-L93"
     },
     {
       "kind": "interface",
@@ -68564,7 +68577,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L92-L99"
+      "specLocation": "_types/analysis/tokenizers.ts#L95-L102"
     },
     {
       "kind": "interface",
@@ -68877,7 +68890,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L101-L106"
+      "specLocation": "_types/analysis/tokenizers.ts#L104-L109"
     },
     {
       "kind": "interface",
@@ -69650,7 +69663,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L113-L116"
+      "specLocation": "_types/analysis/tokenizers.ts#L116-L119"
     },
     {
       "kind": "interface",
@@ -69685,7 +69698,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L108-L111"
+      "specLocation": "_types/analysis/tokenizers.ts#L111-L114"
     },
     {
       "kind": "interface",
@@ -70030,7 +70043,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L118-L121"
+      "specLocation": "_types/analysis/tokenizers.ts#L121-L124"
     },
     {
       "kind": "interface",
@@ -70631,7 +70644,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L123-L125"
+      "specLocation": "_types/analysis/tokenizers.ts#L126-L128"
     },
     {
       "kind": "enum",
@@ -71070,7 +71083,7 @@
         "name": "Tokenizer",
         "namespace": "_types.analysis"
       },
-      "specLocation": "_types/analysis/tokenizers.ts#L137-L139",
+      "specLocation": "_types/analysis/tokenizers.ts#L140-L142",
       "type": {
         "kind": "union_of",
         "items": [
@@ -71118,7 +71131,7 @@
         "name": "TokenizerDefinition",
         "namespace": "_types.analysis"
       },
-      "specLocation": "_types/analysis/tokenizers.ts#L141-L164",
+      "specLocation": "_types/analysis/tokenizers.ts#L144-L167",
       "type": {
         "kind": "union_of",
         "items": [
@@ -71402,7 +71415,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L127-L130"
+      "specLocation": "_types/analysis/tokenizers.ts#L130-L133"
     },
     {
       "kind": "interface",
@@ -71525,7 +71538,7 @@
           }
         }
       ],
-      "specLocation": "_types/analysis/tokenizers.ts#L132-L135"
+      "specLocation": "_types/analysis/tokenizers.ts#L135-L138"
     },
     {
       "kind": "interface",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index 9b34cb7c8b..3ca12f417f 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -4800,14 +4800,14 @@ export interface AnalysisKeywordAnalyzer {
 export interface AnalysisKeywordMarkerTokenFilter extends AnalysisTokenFilterBase {
   type: 'keyword_marker'
   ignore_case?: boolean
-  keywords?: string[]
+  keywords?: string | string[]
   keywords_path?: string
   keywords_pattern?: string
 }
 
 export interface AnalysisKeywordTokenizer extends AnalysisTokenizerBase {
   type: 'keyword'
-  buffer_size: integer
+  buffer_size?: integer
 }
 
 export interface AnalysisKuromojiAnalyzer {
diff --git a/specification/_types/analysis/token_filters.ts b/specification/_types/analysis/token_filters.ts
index b812415666..199ae92fb2 100644
--- a/specification/_types/analysis/token_filters.ts
+++ b/specification/_types/analysis/token_filters.ts
@@ -232,7 +232,7 @@ export class KeepWordsTokenFilter extends TokenFilterBase {
 export class KeywordMarkerTokenFilter extends TokenFilterBase {
   type: 'keyword_marker'
   ignore_case?: boolean
-  keywords?: string[]
+  keywords?: string | string[]
   keywords_path?: string
   keywords_pattern?: string
 }
diff --git a/specification/_types/analysis/tokenizers.ts b/specification/_types/analysis/tokenizers.ts
index 38308bcbee..948149aaeb 100644
--- a/specification/_types/analysis/tokenizers.ts
+++ b/specification/_types/analysis/tokenizers.ts
@@ -67,7 +67,10 @@ export enum TokenChar {
 
 export class KeywordTokenizer extends TokenizerBase {
   type: 'keyword'
-  buffer_size: integer
+  /**
+   * @server_default 256
+   */
+  buffer_size?: integer
 }
 
 export class LetterTokenizer extends TokenizerBase {