diff --git a/src/DDTrace/Integrations/Mongo/MongoClientIntegration.php b/src/DDTrace/Integrations/Mongo/MongoClientIntegration.php
index 2b49ffdf9d4..25c3ad6acbb 100644
--- a/src/DDTrace/Integrations/Mongo/MongoClientIntegration.php
+++ b/src/DDTrace/Integrations/Mongo/MongoClientIntegration.php
@@ -13,6 +13,8 @@ final class MongoClientIntegration extends Integration
 
     protected static function loadIntegration()
     {
+        // MongoClient::__construct ([ string $server = "mongodb://localhost:27017"
+        // [, array $options = array("connect" => TRUE) [, array $driver_options ]]] )
         self::traceMethod('__construct', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_SERVER, Obfuscation::dsn($args[0]));
@@ -25,24 +27,29 @@ protected static function loadIntegration()
                 $span->setTag(Tags\MONGODB_DATABASE, $args[1]['db']);
             }
         });
+        // MongoCollection MongoClient::selectCollection ( string $db , string $collection )
         self::traceMethod('selectCollection', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_DATABASE, $args[0]);
             $span->setTag(Tags\MONGODB_COLLECTION, $args[1]);
         });
+        // MongoDB MongoClient::selectDB ( string $name )
         self::traceMethod('selectDB', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_DATABASE, $args[0]);
         });
+        // bool MongoClient::setReadPreference ( string $read_preference [, array $tags ] )
         self::traceMethod('setReadPreference', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_READ_PREFERENCE, $args[0]);
         });
-        //self::traceMethod('getConnections');
+        // Methods that don't need extra tags added
         self::traceMethod('getHosts');
         self::traceMethod('getReadPreference');
         self::traceMethod('getWriteConcern');
-        //self::traceMethod('listDBs');
+        self::traceMethod('listDBs');
         self::traceMethod('setWriteConcern');
     }
 
+    // If the `db` option isn't provided via the constructor, we extract
+    // the database name from the DSN string if it exists.
     private static function extractDatabaseNameFromDsn($dsn)
     {
         $matches = [];
diff --git a/src/DDTrace/Integrations/Mongo/MongoCollectionIntegration.php b/src/DDTrace/Integrations/Mongo/MongoCollectionIntegration.php
index 21bb0b57d64..55dde1ec91b 100644
--- a/src/DDTrace/Integrations/Mongo/MongoCollectionIntegration.php
+++ b/src/DDTrace/Integrations/Mongo/MongoCollectionIntegration.php
@@ -12,15 +12,18 @@ final class MongoCollectionIntegration extends Integration
 
     protected static function loadIntegration()
     {
+        // MongoCollection::__construct ( MongoDB $db , string $name )
         self::traceMethod('__construct', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_DATABASE, (string) $args[0]);
             $span->setTag(Tags\MONGODB_COLLECTION, $args[1]);
         });
+        // int MongoCollection::count ([ array $query = array() [, array $options = array() ]] )
         self::traceMethod('count', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
             }
         });
+        // array MongoCollection::createDBRef ( mixed $document_or_id )
         self::traceMethod('createDBRef', null, function (Span $span, $ref) {
             if (!is_array($ref)) {
                 return;
@@ -32,24 +35,30 @@ protected static function loadIntegration()
                 $span->setTag(Tags\MONGODB_COLLECTION, $ref['$ref']);
             }
         });
+        // array MongoCollection::distinct ( string $key [, array $query ] )
         self::traceMethod('distinct', function (Span $span, array $args) {
             if (isset($args[1])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[1]));
             }
         });
+        // MongoCursor MongoCollection::find ([ array $query = array() [, array $fields = array() ]] )
         self::traceMethod('find', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
             }
         });
+        // array MongoCollection::findAndModify ( array $query [, array $update [, array $fields [, array $options ]]] )
         self::traceMethod('findAndModify', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
         });
+        // array MongoCollection::findOne ([ array $query = array() [, array $fields = array()
+        // [, array $options = array() ]]] )
         self::traceMethod('findOne', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
             }
         });
+        // array MongoCollection::getDBRef ( array $ref )
         self::traceMethod('getDBRef', function (Span $span, array $args) {
             if (isset($args[0]['$id'])) {
                 $span->setTag(Tags\MONGODB_BSON_ID, $args[0]['$id']);
@@ -58,19 +67,23 @@ protected static function loadIntegration()
                 $span->setTag(Tags\MONGODB_COLLECTION, $args[0]['$ref']);
             }
         });
+        // bool|array MongoCollection::remove ([ array $criteria = array() [, array $options = array() ]] )
         self::traceMethod('remove', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
             }
         });
+        // bool MongoCollection::setReadPreference ( string $read_preference [, array $tags ] )
         self::traceMethod('setReadPreference', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_READ_PREFERENCE, $args[0]);
         });
+        // bool|array MongoCollection::update ( array $criteria , array $new_object [, array $options = array() ] )
         self::traceMethod('update', function (Span $span, array $args) {
             if (isset($args[0])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]));
             }
         });
+        // Methods that don't need extra tags added
         self::traceMethod('aggregate');
         self::traceMethod('aggregateCursor');
         self::traceMethod('batchInsert');
diff --git a/src/DDTrace/Integrations/Mongo/MongoDBIntegration.php b/src/DDTrace/Integrations/Mongo/MongoDBIntegration.php
index d6103da2869..233c7067bc1 100644
--- a/src/DDTrace/Integrations/Mongo/MongoDBIntegration.php
+++ b/src/DDTrace/Integrations/Mongo/MongoDBIntegration.php
@@ -12,6 +12,7 @@ final class MongoDBIntegration extends Integration
 
     protected static function loadIntegration()
     {
+        // array MongoDB::command ( array $command [, array $options = array() [, string &$hash ]] )
         self::traceMethod('command', function (Span $span, array $args) {
             if (isset($args[0]['query'])) {
                 $span->setTag(Tags\MONGODB_QUERY, json_encode($args[0]['query']));
@@ -22,6 +23,7 @@ protected static function loadIntegration()
                 $span->setTag(Tags\MONGODB_TIMEOUT, $args[1]['timeout']);
             }
         });
+        // array MongoDB::createDBRef ( string $collection , mixed $document_or_id )
         self::traceMethod('createDBRef', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_COLLECTION, $args[0]);
         }, function (Span $span, $ref) {
@@ -29,23 +31,29 @@ protected static function loadIntegration()
                 $span->setTag(Tags\MONGODB_BSON_ID, (string) $ref['$id']);
             }
         });
+        // MongoCollection MongoDB::createCollection ( string $name [, array $options ] )
         self::traceMethod('createCollection', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_COLLECTION, $args[0]);
         });
+        // MongoCollection MongoDB::selectCollection ( string $name )
         self::traceMethod('selectCollection', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_COLLECTION, $args[0]);
         });
+        // array MongoDB::getDBRef ( array $ref )
         self::traceMethod('getDBRef', function (Span $span, array $args) {
             if (isset($args[0]['$ref'])) {
                 $span->setTag(Tags\MONGODB_COLLECTION, $args[0]['$ref']);
             }
         });
+        // int MongoDB::setProfilingLevel ( int $level )
         self::traceMethod('setProfilingLevel', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_PROFILING_LEVEL, $args[0]);
         });
+        // bool MongoDB::setReadPreference ( string $read_preference [, array $tags ] )
         self::traceMethod('setReadPreference', function (Span $span, array $args) {
             $span->setTag(Tags\MONGODB_READ_PREFERENCE, $args[0]);
         });
+        // Methods that don't need extra tags added
         self::traceMethod('drop');
         self::traceMethod('execute');
         self::traceMethod('forceError');
diff --git a/tests/Integration/Integrations/Mongo/MongoTest.php b/tests/Integration/Integrations/Mongo/MongoTest.php
index 63ae3badbee..a9a885b11b6 100644
--- a/tests/Integration/Integrations/Mongo/MongoTest.php
+++ b/tests/Integration/Integrations/Mongo/MongoTest.php
@@ -175,11 +175,10 @@ public function testClientMethods($method)
     public function clientMethods()
     {
         return [
-            //['getConnections'],
             ['getHosts'],
             ['getReadPreference'],
             ['getWriteConcern'],
-            //['listDBs'],
+            ['listDBs'],
         ];
     }