diff --git a/output/schema/validation-errors.json b/output/schema/validation-errors.json
index dd1b7f43bf..34717a8197 100644
--- a/output/schema/validation-errors.json
+++ b/output/schema/validation-errors.json
@@ -1,71 +1,5 @@
 {
   "endpointErrors": {
-    "cat.count": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "count": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "eql.search": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "field_caps": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "indices.resolve_index": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "msearch": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "msearch_template": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "open_point_in_time": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "search_mvt": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "search_template": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
-    "sql.query": {
-      "request": [
-        "Request: query parameter 'project_routing' does not exist in the json spec"
-      ],
-      "response": []
-    },
     "streams.status": {
       "request": [
         "Request: query parameter 'master_timeout' does not exist in the json spec",
diff --git a/specification/_json_spec/cat.count.json b/specification/_json_spec/cat.count.json
index fc77804834..360e4d04ce 100644
--- a/specification/_json_spec/cat.count.json
+++ b/specification/_json_spec/cat.count.json
@@ -42,6 +42,10 @@
         "description": "Return help information",
         "default": false
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "s": {
         "type": "list",
         "description": "Comma-separated list of column names or column aliases to sort by"
diff --git a/specification/_json_spec/count.json b/specification/_json_spec/count.json
index a398aec6ae..11c8ec0096 100644
--- a/specification/_json_spec/count.json
+++ b/specification/_json_spec/count.json
@@ -55,6 +55,10 @@
         "type": "string",
         "description": "Specify the node or shard the operation should be performed on (default: random)"
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "routing": {
         "type": "list",
         "description": "A comma-separated list of specific routing values"
diff --git a/specification/_json_spec/eql.search.json b/specification/_json_spec/eql.search.json
index 4aa0c77ea7..2094be69c1 100644
--- a/specification/_json_spec/eql.search.json
+++ b/specification/_json_spec/eql.search.json
@@ -67,6 +67,10 @@
         "options": ["open", "closed", "hidden", "none", "all"],
         "default": "open",
         "description": "Whether to expand wildcard expression to concrete indices that are open, closed or both."
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {
diff --git a/specification/_json_spec/field_caps.json b/specification/_json_spec/field_caps.json
index 51d6924021..04c490f34d 100644
--- a/specification/_json_spec/field_caps.json
+++ b/specification/_json_spec/field_caps.json
@@ -64,6 +64,10 @@
         "type": "boolean",
         "default": true,
         "description": "Include empty fields in result"
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {
diff --git a/specification/_json_spec/indices.resolve_index.json b/specification/_json_spec/indices.resolve_index.json
index d3e23cc24b..1f1c2ae8ee 100644
--- a/specification/_json_spec/indices.resolve_index.json
+++ b/specification/_json_spec/indices.resolve_index.json
@@ -45,6 +45,10 @@
         "options": ["standard", "time_series", "logsdb", "lookup"],
         "default": "",
         "description": "Filter indices by index mode. Comma-separated list of IndexMode. Empty means no filter."
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     }
   }
diff --git a/specification/_json_spec/msearch.json b/specification/_json_spec/msearch.json
index 2aaf0586e2..4c96ce0476 100644
--- a/specification/_json_spec/msearch.json
+++ b/specification/_json_spec/msearch.json
@@ -84,6 +84,10 @@
         "default": "open",
         "description": "Whether to expand wildcard expression to concrete indices that are open, closed or both."
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "routing": {
         "type": "list",
         "description": "A comma-separated list of specific routing values"
diff --git a/specification/_json_spec/msearch_template.json b/specification/_json_spec/msearch_template.json
index 6e955f2583..bfe6cd4a3d 100644
--- a/specification/_json_spec/msearch_template.json
+++ b/specification/_json_spec/msearch_template.json
@@ -51,6 +51,10 @@
         "type": "boolean",
         "description": "Indicates whether network round-trips should be minimized as part of cross-cluster search requests execution",
         "default": "true"
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {
diff --git a/specification/_json_spec/open_point_in_time.json b/specification/_json_spec/open_point_in_time.json
index 1b635bcd7c..144355dfbd 100644
--- a/specification/_json_spec/open_point_in_time.json
+++ b/specification/_json_spec/open_point_in_time.json
@@ -56,6 +56,10 @@
         "type": "number",
         "description": "The number of concurrent shard requests per node executed concurrently when opening this point-in-time. This value should be used to limit the impact of opening the point-in-time on the cluster",
         "default": 5
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {
diff --git a/specification/_json_spec/search_mvt.json b/specification/_json_spec/search_mvt.json
index 2c76555b05..6e84738fa2 100644
--- a/specification/_json_spec/search_mvt.json
+++ b/specification/_json_spec/search_mvt.json
@@ -68,6 +68,10 @@
         "description": "Aggregation used to create a grid for `field`.",
         "default": "geotile"
       },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
+      },
       "size": {
         "type": "int",
         "description": "Maximum number of features to return in the hits layer. Accepts 0-10000.",
diff --git a/specification/_json_spec/search_template.json b/specification/_json_spec/search_template.json
index d203ccea8a..496fe7c9e9 100644
--- a/specification/_json_spec/search_template.json
+++ b/specification/_json_spec/search_template.json
@@ -85,6 +85,10 @@
         "type": "boolean",
         "description": "Indicates whether network round-trips should be minimized as part of cross-cluster search requests execution",
         "default": "true"
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {
diff --git a/specification/_json_spec/sql.query.json b/specification/_json_spec/sql.query.json
index 5600e84e41..fef69b0617 100644
--- a/specification/_json_spec/sql.query.json
+++ b/specification/_json_spec/sql.query.json
@@ -22,6 +22,10 @@
       "format": {
         "type": "string",
         "description": "a short version of the Accept header, e.g. json, yaml"
+      },
+      "project_routing": {
+        "type": "string",
+        "description": "A Lucene query using project metadata tags to limit which projects to search, such as _alias:_origin or _alias:*pr*. Only supported in serverless."
       }
     },
     "body": {