diff --git a/README.md b/README.md
index 08ecc09..88e3777 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,8 @@
 
 - **path_prefix** prefix of target keys (string, required)
 
+- **direct_path_prefix_object** flag to enable treating `path_prefix` as a single object key (boolean, default to `false`). Since list-objects operation on S3 is eventually consistent, using this for a  more reliable way to retrieve a single object when you know the exact object key.
+
 - **endpoint** S3 endpoint login user name (string, optional)
 
 - **region** S3 region. endpoint will be in effect if you specify both of endpoint and region (string, optional)
diff --git a/embulk-input-s3/src/main/java/org/embulk/input/s3/AbstractS3FileInputPlugin.java b/embulk-input-s3/src/main/java/org/embulk/input/s3/AbstractS3FileInputPlugin.java
index 2aa26c8..0096991 100644
--- a/embulk-input-s3/src/main/java/org/embulk/input/s3/AbstractS3FileInputPlugin.java
+++ b/embulk-input-s3/src/main/java/org/embulk/input/s3/AbstractS3FileInputPlugin.java
@@ -82,6 +82,12 @@ public interface PluginTask
         @ConfigDefault("false")
         public boolean getSkipGlacierObjects();
 
+        /**
+         * When this is on, "path_prefix" config will be treated as a single object key,
+         *
+         * Since list-objects operation on S3 is eventually consistent, using this for a
+         * more reliable way to retrieve a single object when you know the exact object key.
+         */
         @Config("direct_path_prefix_object")
         @ConfigDefault("false")
         public boolean getDirectPathPrefixObject();