diff --git a/docs/api_methods_1_x.asciidoc b/docs/api_methods_1_x.asciidoc
index a7c15c720..48796ef2f 100644
--- a/docs/api_methods_1_x.asciidoc
+++ b/docs/api_methods_1_x.asciidoc
@@ -2314,6 +2314,8 @@ The default method is `POST` and the usual <<api-conventions,params and return v
 [horizontal]
 `dryRun`::
 `Boolean` -- Simulate the operation only and return the resulting state
+`explain`::
+`Boolean` -- Return an explanation of why the commands can or cannot be executed
 `filterMetadata`::
 `Boolean` -- Don't return cluster state metadata (default: false)
 `masterTimeout`::
diff --git a/docs/api_methods_master.asciidoc b/docs/api_methods_master.asciidoc
index dc3ea5e1b..27840a370 100644
--- a/docs/api_methods_master.asciidoc
+++ b/docs/api_methods_master.asciidoc
@@ -2314,6 +2314,8 @@ The default method is `POST` and the usual <<api-conventions,params and return v
 [horizontal]
 `dryRun`::
 `Boolean` -- Simulate the operation only and return the resulting state
+`explain`::
+`Boolean` -- Return an explanation of why the commands can or cannot be executed
 `filterMetadata`::
 `Boolean` -- Don't return cluster state metadata (default: false)
 `masterTimeout`::
diff --git a/package.json b/package.json
index 5f222e575..bcce4302d 100644
--- a/package.json
+++ b/package.json
@@ -76,7 +76,7 @@
     "url": "http://github.com/elasticsearch/elasticsearch-js.git"
   },
   "scripts": {
-    "test": "node scripts/generate --branch default && grunt test",
+    "test": "grunt test",
     "generate": "node scripts/generate"
   },
   "engines": {
diff --git a/src/lib/apis/1_x.js b/src/lib/apis/1_x.js
index f69609fb8..c25ac3a8a 100644
--- a/src/lib/apis/1_x.js
+++ b/src/lib/apis/1_x.js
@@ -775,6 +775,7 @@ api.cluster.prototype.putSettings = ca({
  *
  * @param {Object} params - An object with parameters used to carry out this action
  * @param {Boolean} params.dryRun - Simulate the operation only and return the resulting state
+ * @param {Boolean} params.explain - Return an explanation of why the commands can or cannot be executed
  * @param {Boolean} params.filterMetadata - Don't return cluster state metadata (default: false)
  * @param {Date, Number} params.masterTimeout - Explicit operation timeout for connection to master node
  * @param {Date, Number} params.timeout - Explicit operation timeout
@@ -785,6 +786,9 @@ api.cluster.prototype.reroute = ca({
       type: 'boolean',
       name: 'dry_run'
     },
+    explain: {
+      type: 'boolean'
+    },
     filterMetadata: {
       type: 'boolean',
       name: 'filter_metadata'
diff --git a/src/lib/apis/master.js b/src/lib/apis/master.js
index d7fe9b3c4..88a30dc00 100644
--- a/src/lib/apis/master.js
+++ b/src/lib/apis/master.js
@@ -775,6 +775,7 @@ api.cluster.prototype.putSettings = ca({
  *
  * @param {Object} params - An object with parameters used to carry out this action
  * @param {Boolean} params.dryRun - Simulate the operation only and return the resulting state
+ * @param {Boolean} params.explain - Return an explanation of why the commands can or cannot be executed
  * @param {Boolean} params.filterMetadata - Don't return cluster state metadata (default: false)
  * @param {Date, Number} params.masterTimeout - Explicit operation timeout for connection to master node
  * @param {Date, Number} params.timeout - Explicit operation timeout
@@ -785,6 +786,9 @@ api.cluster.prototype.reroute = ca({
       type: 'boolean',
       name: 'dry_run'
     },
+    explain: {
+      type: 'boolean'
+    },
     filterMetadata: {
       type: 'boolean',
       name: 'filter_metadata'