diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Average.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Average.scala
index 94ac4bf09b90..f1ad1fe7d03d 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Average.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Average.scala
@@ -23,6 +23,8 @@ import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.util.TypeUtils
 import org.apache.spark.sql.types._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the average of the values in a group.")
 case class Average(child: Expression) extends DeclarativeAggregate {
 
   override def prettyName: String = "avg"
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Corr.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Corr.scala
index d25f3335ffd9..c25aa0740494 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Corr.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Corr.scala
@@ -29,6 +29,8 @@ import org.apache.spark.sql.types._
  * Definition of Pearson correlation can be found at
  * http://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient
  */
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the Pearson Correlation Coefficient for two columns..")
 case class Corr(
     left: Expression,
     right: Expression,
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Count.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Count.scala
index 663c69e799fb..e688f0c3d67b 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Count.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Count.scala
@@ -21,6 +21,8 @@ import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.types._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the number of items in a group.")
 case class Count(children: Seq[Expression]) extends DeclarativeAggregate {
 
   override def nullable: Boolean = false
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/First.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/First.scala
index 35f57426feaf..be66828207c9 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/First.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/First.scala
@@ -28,6 +28,8 @@ import org.apache.spark.sql.types._
  * is used) its result will not be deterministic (unless the input table is sorted and has
  * a single partition, and we use a single reducer to do the aggregation.).
  */
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the first value in a group.")
 case class First(child: Expression, ignoreNullsExpr: Expression) extends DeclarativeAggregate {
 
   def this(child: Expression) = this(child, Literal.create(false, BooleanType))
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/HyperLogLogPlusPlus.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/HyperLogLogPlusPlus.scala
index e1fd22e36764..6e98b75889bc 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/HyperLogLogPlusPlus.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/HyperLogLogPlusPlus.scala
@@ -48,6 +48,8 @@ import org.apache.spark.sql.types._
  * @param relativeSD the maximum estimation error allowed.
  */
 // scalastyle:on
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the approximate number of distinct items in a group.")
 case class HyperLogLogPlusPlus(
     child: Expression,
     relativeSD: Double = 0.05,
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Kurtosis.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Kurtosis.scala
index c2bf2cb94116..300a5dd46008 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Kurtosis.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Kurtosis.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 
 import org.apache.spark.sql.catalyst.expressions._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the kurtosis of the values in a group.")
 case class Kurtosis(child: Expression,
     mutableAggBufferOffset: Int = 0,
     inputAggBufferOffset: Int = 0)
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Last.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Last.scala
index be7e12d7a233..696360a21665 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Last.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Last.scala
@@ -28,6 +28,8 @@ import org.apache.spark.sql.types._
  * is used) its result will not be deterministic (unless the input table is sorted and has
  * a single partition, and we use a single reducer to do the aggregation.).
  */
+@ExpressionDescription(
+  usage = "_FUNC_(column) -  Aggregate function: returns the last value in a group.")
 case class Last(child: Expression, ignoreNullsExpr: Expression) extends DeclarativeAggregate {
 
   def this(child: Expression) = this(child, Literal.create(false, BooleanType))
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Max.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Max.scala
index 906003188d4f..ea9880006b66 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Max.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Max.scala
@@ -22,6 +22,8 @@ import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.util.TypeUtils
 import org.apache.spark.sql.types._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) -  Aggregate function: returns the maximum value of the expression in a group.")
 case class Max(child: Expression) extends DeclarativeAggregate {
 
   override def children: Seq[Expression] = child :: Nil
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Min.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Min.scala
index 39f7afbd081c..a73c32a1580a 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Min.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Min.scala
@@ -22,7 +22,8 @@ import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.util.TypeUtils
 import org.apache.spark.sql.types._
 
-
+@ExpressionDescription(
+  usage = "_FUNC_(column) -  Aggregate function: returns the minimum value of the expression in a group.")
 case class Min(child: Expression) extends DeclarativeAggregate {
 
   override def children: Seq[Expression] = child :: Nil
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Skewness.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Skewness.scala
index 9411bcea2539..a1d64d660c06 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Skewness.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Skewness.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 
 import org.apache.spark.sql.catalyst.expressions._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the skewness of the values in a group.")
 case class Skewness(child: Expression,
     mutableAggBufferOffset: Int = 0,
     inputAggBufferOffset: Int = 0)
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Stddev.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Stddev.scala
index eec79a9033e3..bd19bbd8a546 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Stddev.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Stddev.scala
@@ -19,6 +19,9 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 
 import org.apache.spark.sql.catalyst.expressions._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) -  Aggregate function: returns the sample standard deviation of " +
+    "the expression in a group.")
 case class StddevSamp(child: Expression,
     mutableAggBufferOffset: Int = 0,
     inputAggBufferOffset: Int = 0)
@@ -50,6 +53,9 @@ case class StddevSamp(child: Expression,
   }
 }
 
+@ExpressionDescription(
+usage = "_FUNC_(column) -  Aggregate function: returns the population standard deviation of" +
+" the expression in a group.")
 case class StddevPop(
     child: Expression,
     mutableAggBufferOffset: Int = 0,
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala
index 08a67ea3df51..57e4872c26a0 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala
@@ -22,6 +22,8 @@ import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.util.TypeUtils
 import org.apache.spark.sql.types._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the sum of all values in the expression.")
 case class Sum(child: Expression) extends DeclarativeAggregate {
 
   override def children: Seq[Expression] = child :: Nil
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Variance.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Variance.scala
index cf3a74030539..ab86fb1b78fe 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Variance.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Variance.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 
 import org.apache.spark.sql.catalyst.expressions._
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) -Aggregate function: returns the unbiased variance of the values in a group.")
 case class VarianceSamp(child: Expression,
     mutableAggBufferOffset: Int = 0,
     inputAggBufferOffset: Int = 0)
@@ -50,6 +52,8 @@ case class VarianceSamp(child: Expression,
   }
 }
 
+@ExpressionDescription(
+  usage = "_FUNC_(column) - Aggregate function: returns the population variance of the values in a group.")
 case class VariancePop(
     child: Expression,
     mutableAggBufferOffset: Int = 0,