diff --git a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
index 60cef3e..74d569d 100644
--- a/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
+++ b/jgvariant-core/src/main/java/eu/mulk/jgvariant/core/Decoder.java
@@ -116,7 +116,8 @@
   /**
    * Creates a new {@link Decoder} from an existing one by applying a function to the result.
    *
-   * @param function the function to apply.
+   * @param decodingFunction the function to apply when decoding.
+   * @param encodingFunction the function to apply when encoding.
    * @return a new, decorated {@link Decoder}.
    * @see java.util.stream.Stream#map
    */
@@ -127,7 +128,8 @@
   /**
    * Creates a new {@link Decoder} from an existing one by applying a function to the input.
    *
-   * @param function the function to apply.
+   * @param decodingFunction the function to apply when decoding.
+   * @param encodingFunction the function to apply when encoding.
    * @return a new, decorated {@link Decoder}.
    * @see java.util.stream.Stream#map
    */
diff --git a/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/Main.java b/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/Main.java
index 64e375a..bca6ad9 100644
--- a/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/Main.java
+++ b/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/Main.java
@@ -12,7 +12,50 @@
 /**
  * A command line tool to read and manipulate GVariant-formatted files.
  *
+ * <p>Implements a tool called {@code jgvariant} that can be used to
+ * manipulate GVariant-formatted files from the command line.
+ *
  * <p>Also provides ways to manipulate OSTree repositories.
+ *
+ * <p>Usage example (dumping the contents of an OSTree summary file):
+ *
+ * {@snippet lang="sh" :
+ * $ jgvariant ostree summary read ./jgvariant-ostree/src/test/resources/ostree/summary
+ * }
+ *
+ * <p>Output:
+ *
+ * {@snippet lang="json" :
+ * {
+ *     "entries": [
+ *         {
+ *             "ref": "mulkos/1.x/amd64",
+ *             "value": {
+ *                 "checksum": "66ff167ff35ce87daac817447a9490a262ee75f095f017716a6eb1a9d9eb3350",
+ *                 "metadata": {
+ *                     "fields": {
+ *                         "ostree.commit.timestamp": 1640537170
+ *                     }
+ *                 },
+ *                 "size": 214
+ *             }
+ *         }
+ *     ],
+ *     "metadata": {
+ *         "fields": {
+ *             "ostree.summary.last-modified": 1640537300,
+ *             "ostree.summary.tombstone-commits": false,
+ *             "ostree.static-deltas": {
+ *                 "3d3b3329dca38871f29aeda1bf5854d76c707fa269759a899d0985c91815fe6f-66ff167ff35ce87daac817447a9490a262ee75f095f017716a6eb1a9d9eb3350": "03738040e28e7662e9c9d2599c530ea974e642c9f87e6c00cbaa39a0cdac8d44",
+ *                 "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52": "f481144629474bd88c106e45ac405ebd75b324b0655af1aec14b31786ae1fd61",
+ *                 "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52-3d3b3329dca38871f29aeda1bf5854d76c707fa269759a899d0985c91815fe6f": "2c6a07bc1cf4d7ce7d00f82d7d2d6d156fd0e31d476851b46dc2306b181b064a"
+ *             },
+ *             "ostree.summary.mode": "bare",
+ *             "ostree.summary.indexed-deltas": true
+ *         }
+ *     }
+ * }
+ * }
  */
 public final class Main {
   static {
diff --git a/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/package-info.java b/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/package-info.java
index da5c3ba..54a4fff 100644
--- a/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/package-info.java
+++ b/jgvariant-tool/src/main/java/eu/mulk/jgvariant/tool/package-info.java
@@ -2,6 +2,12 @@
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 
+/**
+ * The {@code jgvariant} command line tool.
+ *
+ * <p>The {@link eu.mulk.jgvariant.tool.Main} class defines a tool called {@code jgvariant} that can
+ * be used to manipulate GVariant-formatted files from the command line.
+ */
 @API(status = API.Status.INTERNAL)
 package eu.mulk.jgvariant.tool;
 
diff --git a/jgvariant-tool/src/main/java/module-info.java b/jgvariant-tool/src/main/java/module-info.java
index add77c0..3f457ea 100644
--- a/jgvariant-tool/src/main/java/module-info.java
+++ b/jgvariant-tool/src/main/java/module-info.java
@@ -2,7 +2,58 @@
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-module eu.mulk.jgvariant.tool {
+/**
+ * The {@code jgvariant} command line tool.
+ *
+ * <p>The {@link eu.mulk.jgvariant.tool} module contains a tool called
+ * {@code jgvariant} that can be used to manipulate GVariant-formatted
+ * files from the command line.  Its primary purpose is to enable the
+ * scripting of OSTree repository management tasks.
+ *
+ * <p>The {@link eu.mulk.jgvariant.tool.Main} class defines the entry point
+ * of the tool.
+ *
+ * <p>Usage example (dumping the contents of an OSTree summary file):
+ *
+ * {@snippet lang="sh" :
+ * $ jgvariant ostree summary read ./jgvariant-ostree/src/test/resources/ostree/summary
+ * }
+ *
+ * <p>Output:
+ *
+ * {@snippet lang="json" :
+ * {
+ *     "entries": [
+ *         {
+ *             "ref": "mulkos/1.x/amd64",
+ *             "value": {
+ *                 "checksum": "66ff167ff35ce87daac817447a9490a262ee75f095f017716a6eb1a9d9eb3350",
+ *                 "metadata": {
+ *                     "fields": {
+ *                         "ostree.commit.timestamp": 1640537170
+ *                     }
+ *                 },
+ *                 "size": 214
+ *             }
+ *         }
+ *     ],
+ *     "metadata": {
+ *         "fields": {
+ *             "ostree.summary.last-modified": 1640537300,
+ *             "ostree.summary.tombstone-commits": false,
+ *             "ostree.static-deltas": {
+ *                 "3d3b3329dca38871f29aeda1bf5854d76c707fa269759a899d0985c91815fe6f-66ff167ff35ce87daac817447a9490a262ee75f095f017716a6eb1a9d9eb3350": "03738040e28e7662e9c9d2599c530ea974e642c9f87e6c00cbaa39a0cdac8d44",
+ *                 "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52": "f481144629474bd88c106e45ac405ebd75b324b0655af1aec14b31786ae1fd61",
+ *                 "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52-3d3b3329dca38871f29aeda1bf5854d76c707fa269759a899d0985c91815fe6f": "2c6a07bc1cf4d7ce7d00f82d7d2d6d156fd0e31d476851b46dc2306b181b064a"
+ *             },
+ *             "ostree.summary.mode": "bare",
+ *             "ostree.summary.indexed-deltas": true
+ *         }
+ *     }
+ * }
+ * }
+ */
+ module eu.mulk.jgvariant.tool {
   requires transitive eu.mulk.jgvariant.ostree;
   requires info.picocli;
   requires jakarta.json;