diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index 9f8c94e886..2b4d924064 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -41879,7 +41879,11 @@
             "$ref": "#/components/schemas/indices._types:Queries"
           },
           "similarity": {
-            "$ref": "#/components/schemas/indices._types:SettingsSimilarity"
+            "description": "Configure custom similarity settings to customize how search results are scored.",
+            "type": "object",
+            "additionalProperties": {
+              "$ref": "#/components/schemas/indices._types:SettingsSimilarity"
+            }
           },
           "mapping": {
             "$ref": "#/components/schemas/indices._types:MappingLimitSettings"
@@ -44926,36 +44930,45 @@
         ]
       },
       "indices._types:SettingsSimilarity": {
-        "type": "object",
-        "properties": {
-          "bm25": {
+        "discriminator": {
+          "propertyName": "type"
+        },
+        "oneOf": [
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityBm25"
           },
-          "dfi": {
+          {
+            "$ref": "#/components/schemas/indices._types:SettingsSimilarityBoolean"
+          },
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityDfi"
           },
-          "dfr": {
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityDfr"
           },
-          "ib": {
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityIb"
           },
-          "lmd": {
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityLmd"
           },
-          "lmj": {
+          {
             "$ref": "#/components/schemas/indices._types:SettingsSimilarityLmj"
           },
-          "scripted_tfidf": {
-            "$ref": "#/components/schemas/indices._types:SettingsSimilarityScriptedTfidf"
+          {
+            "$ref": "#/components/schemas/indices._types:SettingsSimilarityScripted"
           }
-        },
-        "minProperties": 1,
-        "maxProperties": 1
+        ]
       },
       "indices._types:SettingsSimilarityBm25": {
         "type": "object",
         "properties": {
+          "type": {
+            "type": "string",
+            "enum": [
+              "BM25"
+            ]
+          },
           "b": {
             "type": "number"
           },
@@ -44964,37 +44977,42 @@
           },
           "k1": {
             "type": "number"
-          },
+          }
+        },
+        "required": [
+          "type"
+        ]
+      },
+      "indices._types:SettingsSimilarityBoolean": {
+        "type": "object",
+        "properties": {
           "type": {
             "type": "string",
             "enum": [
-              "BM25"
+              "boolean"
             ]
           }
         },
         "required": [
-          "b",
-          "discount_overlaps",
-          "k1",
           "type"
         ]
       },
       "indices._types:SettingsSimilarityDfi": {
         "type": "object",
         "properties": {
-          "independence_measure": {
-            "$ref": "#/components/schemas/_types:DFIIndependenceMeasure"
-          },
           "type": {
             "type": "string",
             "enum": [
               "DFI"
             ]
+          },
+          "independence_measure": {
+            "$ref": "#/components/schemas/_types:DFIIndependenceMeasure"
           }
         },
         "required": [
-          "independence_measure",
-          "type"
+          "type",
+          "independence_measure"
         ]
       },
       "_types:DFIIndependenceMeasure": {
@@ -45008,6 +45026,12 @@
       "indices._types:SettingsSimilarityDfr": {
         "type": "object",
         "properties": {
+          "type": {
+            "type": "string",
+            "enum": [
+              "DFR"
+            ]
+          },
           "after_effect": {
             "$ref": "#/components/schemas/_types:DFRAfterEffect"
           },
@@ -45016,19 +45040,13 @@
           },
           "normalization": {
             "$ref": "#/components/schemas/_types:Normalization"
-          },
-          "type": {
-            "type": "string",
-            "enum": [
-              "DFR"
-            ]
           }
         },
         "required": [
+          "type",
           "after_effect",
           "basic_model",
-          "normalization",
-          "type"
+          "normalization"
         ]
       },
       "_types:DFRAfterEffect": {
@@ -45064,6 +45082,12 @@
       "indices._types:SettingsSimilarityIb": {
         "type": "object",
         "properties": {
+          "type": {
+            "type": "string",
+            "enum": [
+              "IB"
+            ]
+          },
           "distribution": {
             "$ref": "#/components/schemas/_types:IBDistribution"
           },
@@ -45072,19 +45096,13 @@
           },
           "normalization": {
             "$ref": "#/components/schemas/_types:Normalization"
-          },
-          "type": {
-            "type": "string",
-            "enum": [
-              "IB"
-            ]
           }
         },
         "required": [
+          "type",
           "distribution",
           "lambda",
-          "normalization",
-          "type"
+          "normalization"
         ]
       },
       "_types:IBDistribution": {
@@ -45104,55 +45122,56 @@
       "indices._types:SettingsSimilarityLmd": {
         "type": "object",
         "properties": {
-          "mu": {
-            "type": "number"
-          },
           "type": {
             "type": "string",
             "enum": [
               "LMDirichlet"
             ]
+          },
+          "mu": {
+            "type": "number"
           }
         },
         "required": [
-          "mu",
           "type"
         ]
       },
       "indices._types:SettingsSimilarityLmj": {
         "type": "object",
         "properties": {
-          "lambda": {
-            "type": "number"
-          },
           "type": {
             "type": "string",
             "enum": [
               "LMJelinekMercer"
             ]
+          },
+          "lambda": {
+            "type": "number"
           }
         },
         "required": [
-          "lambda",
           "type"
         ]
       },
-      "indices._types:SettingsSimilarityScriptedTfidf": {
+      "indices._types:SettingsSimilarityScripted": {
         "type": "object",
         "properties": {
-          "script": {
-            "$ref": "#/components/schemas/_types:Script"
-          },
           "type": {
             "type": "string",
             "enum": [
               "scripted"
             ]
+          },
+          "script": {
+            "$ref": "#/components/schemas/_types:Script"
+          },
+          "weight_script": {
+            "$ref": "#/components/schemas/_types:Script"
           }
         },
         "required": [
-          "script",
-          "type"
+          "type",
+          "script"
         ]
       },
       "indices._types:MappingLimitSettings": {
diff --git a/output/schema/schema.json b/output/schema/schema.json
index 44eb0ff7fd..b7897b1b41 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -111017,7 +111017,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L401-L403"
+      "specLocation": "indices/_types/IndexSettings.ts#L405-L407"
     },
     {
       "kind": "interface",
@@ -111687,7 +111687,7 @@
         "name": "IndexCheckOnStartup",
         "namespace": "indices._types"
       },
-      "specLocation": "indices/_types/IndexSettings.ts#L256-L263"
+      "specLocation": "indices/_types/IndexSettings.ts#L260-L267"
     },
     {
       "kind": "interface",
@@ -112133,7 +112133,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L248-L254"
+      "specLocation": "indices/_types/IndexSettings.ts#L252-L258"
     },
     {
       "attachedBehaviors": [
@@ -112869,10 +112869,21 @@
           "name": "similarity",
           "required": false,
           "type": {
-            "kind": "instance_of",
-            "type": {
-              "name": "SettingsSimilarity",
-              "namespace": "indices._types"
+            "key": {
+              "kind": "instance_of",
+              "type": {
+                "name": "string",
+                "namespace": "_builtins"
+              }
+            },
+            "kind": "dictionary_of",
+            "singleKey": false,
+            "value": {
+              "kind": "instance_of",
+              "type": {
+                "name": "SettingsSimilarity",
+                "namespace": "indices._types"
+              }
             }
           }
         },
@@ -113044,7 +113055,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L313-L319"
+      "specLocation": "indices/_types/IndexSettings.ts#L317-L323"
     },
     {
       "kind": "interface",
@@ -113137,7 +113148,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L270-L303"
+      "specLocation": "indices/_types/IndexSettings.ts#L274-L307"
     },
     {
       "kind": "interface",
@@ -113159,7 +113170,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L305-L311"
+      "specLocation": "indices/_types/IndexSettings.ts#L309-L315"
     },
     {
       "kind": "interface",
@@ -113191,7 +113202,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L321-L324"
+      "specLocation": "indices/_types/IndexSettings.ts#L325-L328"
     },
     {
       "kind": "interface",
@@ -113548,7 +113559,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L265-L268"
+      "specLocation": "indices/_types/IndexSettings.ts#L269-L272"
     },
     {
       "kind": "interface",
@@ -113569,7 +113580,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L537-L539"
+      "specLocation": "indices/_types/IndexSettings.ts#L541-L543"
     },
     {
       "kind": "interface",
@@ -113591,7 +113602,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L541-L548"
+      "specLocation": "indices/_types/IndexSettings.ts#L545-L552"
     },
     {
       "kind": "interface",
@@ -113645,7 +113656,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L550-L555"
+      "specLocation": "indices/_types/IndexSettings.ts#L554-L559"
     },
     {
       "kind": "interface",
@@ -113669,7 +113680,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L557-L564"
+      "specLocation": "indices/_types/IndexSettings.ts#L561-L568"
     },
     {
       "kind": "enum",
@@ -113792,7 +113803,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L405-L418"
+      "specLocation": "indices/_types/IndexSettings.ts#L409-L422"
     },
     {
       "kind": "interface",
@@ -113815,7 +113826,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L430-L437"
+      "specLocation": "indices/_types/IndexSettings.ts#L434-L441"
     },
     {
       "kind": "interface",
@@ -113837,7 +113848,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L467-L473"
+      "specLocation": "indices/_types/IndexSettings.ts#L471-L477"
     },
     {
       "kind": "interface",
@@ -113859,7 +113870,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L458-L465"
+      "specLocation": "indices/_types/IndexSettings.ts#L462-L469"
     },
     {
       "kind": "interface",
@@ -113882,7 +113893,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L439-L447"
+      "specLocation": "indices/_types/IndexSettings.ts#L443-L451"
     },
     {
       "kind": "interface",
@@ -113905,7 +113916,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L449-L456"
+      "specLocation": "indices/_types/IndexSettings.ts#L453-L460"
     },
     {
       "kind": "interface",
@@ -113928,7 +113939,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L420-L428"
+      "specLocation": "indices/_types/IndexSettings.ts#L424-L432"
     },
     {
       "kind": "interface",
@@ -113949,7 +113960,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L326-L328"
+      "specLocation": "indices/_types/IndexSettings.ts#L330-L332"
     },
     {
       "kind": "interface",
@@ -113999,7 +114010,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L330-L333"
+      "specLocation": "indices/_types/IndexSettings.ts#L334-L337"
     },
     {
       "kind": "interface",
@@ -114057,7 +114068,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L397-L399"
+      "specLocation": "indices/_types/IndexSettings.ts#L401-L403"
     },
     {
       "kind": "interface",
@@ -114100,7 +114111,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L239-L242"
+      "specLocation": "indices/_types/IndexSettings.ts#L243-L246"
     },
     {
       "kind": "enum",
@@ -114193,7 +114204,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L229-L232"
+      "specLocation": "indices/_types/IndexSettings.ts#L233-L236"
     },
     {
       "kind": "interface",
@@ -114215,7 +114226,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L224-L227"
+      "specLocation": "indices/_types/IndexSettings.ts#L228-L231"
     },
     {
       "kind": "interface",
@@ -114245,7 +114256,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L244-L246"
+      "specLocation": "indices/_types/IndexSettings.ts#L248-L250"
     },
     {
       "kind": "interface",
@@ -114277,97 +114288,79 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L234-L237"
+      "specLocation": "indices/_types/IndexSettings.ts#L238-L241"
     },
     {
-      "kind": "interface",
+      "kind": "type_alias",
       "name": {
         "name": "SettingsSimilarity",
         "namespace": "indices._types"
       },
-      "properties": [
-        {
-          "name": "bm25",
-          "required": false,
-          "type": {
+      "specLocation": "indices/_types/IndexSettings.ts#L169-L180",
+      "type": {
+        "items": [
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityBm25",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "dfi",
-          "required": false,
-          "type": {
+          },
+          {
+            "kind": "instance_of",
+            "type": {
+              "name": "SettingsSimilarityBoolean",
+              "namespace": "indices._types"
+            }
+          },
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityDfi",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "dfr",
-          "required": false,
-          "type": {
+          },
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityDfr",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "ib",
-          "required": false,
-          "type": {
+          },
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityIb",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "lmd",
-          "required": false,
-          "type": {
+          },
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityLmd",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "lmj",
-          "required": false,
-          "type": {
+          },
+          {
             "kind": "instance_of",
             "type": {
               "name": "SettingsSimilarityLmj",
               "namespace": "indices._types"
             }
-          }
-        },
-        {
-          "name": "scripted_tfidf",
-          "required": false,
-          "type": {
+          },
+          {
             "kind": "instance_of",
             "type": {
-              "name": "SettingsSimilarityScriptedTfidf",
+              "name": "SettingsSimilarityScripted",
               "namespace": "indices._types"
             }
           }
-        }
-      ],
-      "specLocation": "indices/_types/IndexSettings.ts#L169-L181",
+        ],
+        "kind": "union_of"
+      },
       "variants": {
-        "kind": "container",
-        "nonExhaustive": true
+        "kind": "internal_tag",
+        "tag": "type"
       }
     },
     {
@@ -114378,8 +114371,16 @@
       },
       "properties": [
         {
-          "name": "b",
+          "name": "type",
           "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "BM25"
+          }
+        },
+        {
+          "name": "b",
+          "required": false,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -114390,7 +114391,7 @@
         },
         {
           "name": "discount_overlaps",
-          "required": true,
+          "required": false,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -114401,7 +114402,7 @@
         },
         {
           "name": "k1",
-          "required": true,
+          "required": false,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -114409,17 +114410,27 @@
               "namespace": "_types"
             }
           }
-        },
+        }
+      ],
+      "specLocation": "indices/_types/IndexSettings.ts#L186-L191"
+    },
+    {
+      "kind": "interface",
+      "name": {
+        "name": "SettingsSimilarityBoolean",
+        "namespace": "indices._types"
+      },
+      "properties": [
         {
           "name": "type",
           "required": true,
           "type": {
             "kind": "literal_value",
-            "value": "BM25"
+            "value": "boolean"
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L183-L188"
+      "specLocation": "indices/_types/IndexSettings.ts#L182-L184"
     },
     {
       "kind": "interface",
@@ -114428,6 +114439,14 @@
         "namespace": "indices._types"
       },
       "properties": [
+        {
+          "name": "type",
+          "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "DFI"
+          }
+        },
         {
           "name": "independence_measure",
           "required": true,
@@ -114438,17 +114457,9 @@
               "namespace": "_types"
             }
           }
-        },
-        {
-          "name": "type",
-          "required": true,
-          "type": {
-            "kind": "literal_value",
-            "value": "DFI"
-          }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L190-L193"
+      "specLocation": "indices/_types/IndexSettings.ts#L193-L196"
     },
     {
       "kind": "interface",
@@ -114457,6 +114468,14 @@
         "namespace": "indices._types"
       },
       "properties": [
+        {
+          "name": "type",
+          "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "DFR"
+          }
+        },
         {
           "name": "after_effect",
           "required": true,
@@ -114489,17 +114508,9 @@
               "namespace": "_types"
             }
           }
-        },
-        {
-          "name": "type",
-          "required": true,
-          "type": {
-            "kind": "literal_value",
-            "value": "DFR"
-          }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L195-L200"
+      "specLocation": "indices/_types/IndexSettings.ts#L198-L203"
     },
     {
       "kind": "interface",
@@ -114508,6 +114519,14 @@
         "namespace": "indices._types"
       },
       "properties": [
+        {
+          "name": "type",
+          "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "IB"
+          }
+        },
         {
           "name": "distribution",
           "required": true,
@@ -114540,17 +114559,9 @@
               "namespace": "_types"
             }
           }
-        },
-        {
-          "name": "type",
-          "required": true,
-          "type": {
-            "kind": "literal_value",
-            "value": "IB"
-          }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L202-L207"
+      "specLocation": "indices/_types/IndexSettings.ts#L205-L210"
     },
     {
       "kind": "interface",
@@ -114560,26 +114571,26 @@
       },
       "properties": [
         {
-          "name": "mu",
+          "name": "type",
           "required": true,
           "type": {
-            "kind": "instance_of",
-            "type": {
-              "name": "integer",
-              "namespace": "_types"
-            }
+            "kind": "literal_value",
+            "value": "LMDirichlet"
           }
         },
         {
-          "name": "type",
-          "required": true,
+          "name": "mu",
+          "required": false,
           "type": {
-            "kind": "literal_value",
-            "value": "LMDirichlet"
+            "kind": "instance_of",
+            "type": {
+              "name": "double",
+              "namespace": "_types"
+            }
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L209-L212"
+      "specLocation": "indices/_types/IndexSettings.ts#L212-L215"
     },
     {
       "kind": "interface",
@@ -114589,8 +114600,16 @@
       },
       "properties": [
         {
-          "name": "lambda",
+          "name": "type",
           "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "LMJelinekMercer"
+          }
+        },
+        {
+          "name": "lambda",
+          "required": false,
           "type": {
             "kind": "instance_of",
             "type": {
@@ -114598,25 +114617,25 @@
               "namespace": "_types"
             }
           }
-        },
-        {
-          "name": "type",
-          "required": true,
-          "type": {
-            "kind": "literal_value",
-            "value": "LMJelinekMercer"
-          }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L214-L217"
+      "specLocation": "indices/_types/IndexSettings.ts#L217-L220"
     },
     {
       "kind": "interface",
       "name": {
-        "name": "SettingsSimilarityScriptedTfidf",
+        "name": "SettingsSimilarityScripted",
         "namespace": "indices._types"
       },
       "properties": [
+        {
+          "name": "type",
+          "required": true,
+          "type": {
+            "kind": "literal_value",
+            "value": "scripted"
+          }
+        },
         {
           "name": "script",
           "required": true,
@@ -114629,15 +114648,18 @@
           }
         },
         {
-          "name": "type",
-          "required": true,
+          "name": "weight_script",
+          "required": false,
           "type": {
-            "kind": "literal_value",
-            "value": "scripted"
+            "kind": "instance_of",
+            "type": {
+              "name": "Script",
+              "namespace": "_types"
+            }
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L219-L222"
+      "specLocation": "indices/_types/IndexSettings.ts#L222-L226"
     },
     {
       "kind": "interface",
@@ -114691,7 +114713,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L475-L480"
+      "specLocation": "indices/_types/IndexSettings.ts#L479-L484"
     },
     {
       "kind": "interface",
@@ -114745,7 +114767,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L487-L492"
+      "specLocation": "indices/_types/IndexSettings.ts#L491-L496"
     },
     {
       "kind": "interface",
@@ -114777,7 +114799,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L482-L485"
+      "specLocation": "indices/_types/IndexSettings.ts#L486-L489"
     },
     {
       "kind": "interface",
@@ -114845,7 +114867,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L494-L503"
+      "specLocation": "indices/_types/IndexSettings.ts#L498-L507"
     },
     {
       "isOpen": true,
@@ -114875,7 +114897,7 @@
         "name": "StorageType",
         "namespace": "indices._types"
       },
-      "specLocation": "indices/_types/IndexSettings.ts#L505-L535"
+      "specLocation": "indices/_types/IndexSettings.ts#L509-L539"
     },
     {
       "kind": "interface",
@@ -115032,7 +115054,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L335-L357"
+      "specLocation": "indices/_types/IndexSettings.ts#L339-L361"
     },
     {
       "kind": "enum",
@@ -115056,7 +115078,7 @@
         "name": "TranslogDurability",
         "namespace": "indices._types"
       },
-      "specLocation": "indices/_types/IndexSettings.ts#L359-L374"
+      "specLocation": "indices/_types/IndexSettings.ts#L363-L378"
     },
     {
       "kind": "interface",
@@ -115092,7 +115114,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/IndexSettings.ts#L376-L395"
+      "specLocation": "indices/_types/IndexSettings.ts#L380-L399"
     },
     {
       "kind": "enum",
@@ -155897,9 +155919,7 @@
           },
           {
             "availability": {
-              "serverless": {
-                "since": "8.12.0"
-              },
+              "serverless": {},
               "stack": {
                 "since": "8.12.0"
               }
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index dd4728d8e4..9b46125716 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -9883,7 +9883,7 @@ export interface IndicesIndexSettingsKeys {
   settings?: IndicesIndexSettings
   time_series?: IndicesIndexSettingsTimeSeries
   queries?: IndicesQueries
-  similarity?: IndicesSettingsSimilarity
+  similarity?: Record<string, IndicesSettingsSimilarity>
   mapping?: IndicesMappingLimitSettings
   'indexing.slowlog'?: IndicesIndexingSlowlogSettings
   indexing_pressure?: IndicesIndexingPressure
@@ -10061,55 +10061,52 @@ export interface IndicesSettingsSearch {
   slowlog?: IndicesSlowlogSettings
 }
 
-export interface IndicesSettingsSimilarity {
-  bm25?: IndicesSettingsSimilarityBm25
-  dfi?: IndicesSettingsSimilarityDfi
-  dfr?: IndicesSettingsSimilarityDfr
-  ib?: IndicesSettingsSimilarityIb
-  lmd?: IndicesSettingsSimilarityLmd
-  lmj?: IndicesSettingsSimilarityLmj
-  scripted_tfidf?: IndicesSettingsSimilarityScriptedTfidf
-}
+export type IndicesSettingsSimilarity = IndicesSettingsSimilarityBm25 | IndicesSettingsSimilarityBoolean | IndicesSettingsSimilarityDfi | IndicesSettingsSimilarityDfr | IndicesSettingsSimilarityIb | IndicesSettingsSimilarityLmd | IndicesSettingsSimilarityLmj | IndicesSettingsSimilarityScripted
 
 export interface IndicesSettingsSimilarityBm25 {
-  b: double
-  discount_overlaps: boolean
-  k1: double
   type: 'BM25'
+  b?: double
+  discount_overlaps?: boolean
+  k1?: double
+}
+
+export interface IndicesSettingsSimilarityBoolean {
+  type: 'boolean'
 }
 
 export interface IndicesSettingsSimilarityDfi {
-  independence_measure: DFIIndependenceMeasure
   type: 'DFI'
+  independence_measure: DFIIndependenceMeasure
 }
 
 export interface IndicesSettingsSimilarityDfr {
+  type: 'DFR'
   after_effect: DFRAfterEffect
   basic_model: DFRBasicModel
   normalization: Normalization
-  type: 'DFR'
 }
 
 export interface IndicesSettingsSimilarityIb {
+  type: 'IB'
   distribution: IBDistribution
   lambda: IBLambda
   normalization: Normalization
-  type: 'IB'
 }
 
 export interface IndicesSettingsSimilarityLmd {
-  mu: integer
   type: 'LMDirichlet'
+  mu?: double
 }
 
 export interface IndicesSettingsSimilarityLmj {
-  lambda: double
   type: 'LMJelinekMercer'
+  lambda?: double
 }
 
-export interface IndicesSettingsSimilarityScriptedTfidf {
-  script: Script
+export interface IndicesSettingsSimilarityScripted {
   type: 'scripted'
+  script: Script
+  weight_script?: Script
 }
 
 export interface IndicesSlowlogSettings {
diff --git a/specification/indices/_types/IndexSettings.ts b/specification/indices/_types/IndexSettings.ts
index df538542a0..3ffce4f1f7 100644
--- a/specification/indices/_types/IndexSettings.ts
+++ b/specification/indices/_types/IndexSettings.ts
@@ -150,7 +150,7 @@ export class IndexSettings
   /**
    * Configure custom similarity settings to customize how search results are scored.
    */
-  similarity?: SettingsSimilarity
+  similarity?: Dictionary<string, SettingsSimilarity>
   /**
    * Enable or disable dynamic mapping for an index.
    */
@@ -167,58 +167,62 @@ export class IndexSettings
 }
 
 /**
- * @variants container
- * @non_exhaustive
+ * @variants internal tag='type'
  */
-export class SettingsSimilarity {
-  bm25?: SettingsSimilarityBm25
-  dfi?: SettingsSimilarityDfi
-  dfr?: SettingsSimilarityDfr
-  ib?: SettingsSimilarityIb
-  lmd?: SettingsSimilarityLmd
-  lmj?: SettingsSimilarityLmj
-  scripted_tfidf?: SettingsSimilarityScriptedTfidf
+export type SettingsSimilarity =
+  | SettingsSimilarityBm25
+  | SettingsSimilarityBoolean
+  | SettingsSimilarityDfi
+  | SettingsSimilarityDfr
+  | SettingsSimilarityIb
+  | SettingsSimilarityLmd
+  | SettingsSimilarityLmj
+  | SettingsSimilarityScripted
+
+export class SettingsSimilarityBoolean {
+  type: 'boolean'
 }
 
 export class SettingsSimilarityBm25 {
-  b: double
-  discount_overlaps: boolean
-  k1: double
   type: 'BM25'
+  b?: double
+  discount_overlaps?: boolean
+  k1?: double
 }
 
 export class SettingsSimilarityDfi {
-  independence_measure: DFIIndependenceMeasure
   type: 'DFI'
+  independence_measure: DFIIndependenceMeasure
 }
 
 export class SettingsSimilarityDfr {
+  type: 'DFR'
   after_effect: DFRAfterEffect
   basic_model: DFRBasicModel
   normalization: Normalization
-  type: 'DFR'
 }
 
 export class SettingsSimilarityIb {
+  type: 'IB'
   distribution: IBDistribution
   lambda: IBLambda
   normalization: Normalization
-  type: 'IB'
 }
 
 export class SettingsSimilarityLmd {
-  mu: integer
   type: 'LMDirichlet'
+  mu?: double
 }
 
 export class SettingsSimilarityLmj {
-  lambda: double
   type: 'LMJelinekMercer'
+  lambda?: double
 }
 
-export class SettingsSimilarityScriptedTfidf {
-  script: Script
+export class SettingsSimilarityScripted {
   type: 'scripted'
+  script: Script
+  weight_script?: Script
 }
 
 export class SettingsHighlight {