diff --git a/lib/fluent/buffer.rb b/lib/fluent/buffer.rb
index 4b06de4bf3..30dda85c54 100644
--- a/lib/fluent/buffer.rb
+++ b/lib/fluent/buffer.rb
@@ -139,7 +139,9 @@ def enable_parallel(b=true)
     # This configuration assumes plugins to send records to a remote server.
     # Local file based plugins which should provide more reliability and efficiency
     # should override buffer_chunk_limit with a larger size.
+    desc 'The size of each buffer chunk.'
     config_param :buffer_chunk_limit, :size, :default => 8*1024*1024
+    desc 'The length limit of the chunk queue.'
     config_param :buffer_queue_limit, :integer, :default => 256
 
     alias chunk_limit buffer_chunk_limit
diff --git a/lib/fluent/plugin/buf_file.rb b/lib/fluent/plugin/buf_file.rb
index bce9bc41e9..21a015c16d 100644
--- a/lib/fluent/plugin/buf_file.rb
+++ b/lib/fluent/plugin/buf_file.rb
@@ -95,7 +95,9 @@ def initialize
       @uri_parser = URI::Parser.new
     end
 
+    desc 'The path where buffer chunks are stored.'
     config_param :buffer_path, :string
+    desc 'If true, queued chunks are flushed at shutdown process.'
     config_param :flush_at_shutdown, :bool, :default => false
 
     # 'symlink_path' is currently only for out_file.
diff --git a/lib/fluent/plugin/buf_memory.rb b/lib/fluent/plugin/buf_memory.rb
index f725d503d5..81d69256d8 100644
--- a/lib/fluent/plugin/buf_memory.rb
+++ b/lib/fluent/plugin/buf_memory.rb
@@ -70,6 +70,7 @@ def initialize
       super
     end
 
+    desc 'If true, queued chunks are flushed at shutdown process. Otherwise queued chunks are discarded'
     config_param :flush_at_shutdown, :bool, :default => true
     # Overwrite default BasicBuffer#buffer_queue_limit
     # to limit total memory usage upto 512MB.