Expand TagKey and TagSet Javadocs.

2 files changed, 10 insertions, 3 deletions

diff --git a/core/src/main/java/com/google/instrumentation/tags/TagKey.java b/core/src/main/java/com/google/instrumentation/tags/TagKey.java
index ea6b0518..5787863c 100644
--- a/core/src/main/java/com/google/instrumentation/tags/TagKey.java
+++ b/core/src/main/java/com/google/instrumentation/tags/TagKey.java
@@ -22,9 +22,10 @@ import com.google.instrumentation.internal.StringUtil;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * Tag key.
+ * A key to a value stored in a {@link TagSet}.
  *
- * @param <TagValueT> The type of value that can be paired with this {@code TagKey}.
+ * @param <TagValueT> The type of value that can be paired with this {@code TagKey}. {@code TagKey}s
+ *     can only be instantiated with types {@code String}, {@code Long}, and {@code Boolean}.
  */
 @Immutable
 @AutoValue
diff --git a/core/src/main/java/com/google/instrumentation/tags/TagSet.java b/core/src/main/java/com/google/instrumentation/tags/TagSet.java
index 17955b0f..7b4f3891 100644
--- a/core/src/main/java/com/google/instrumentation/tags/TagSet.java
+++ b/core/src/main/java/com/google/instrumentation/tags/TagSet.java
@@ -16,7 +16,13 @@ package com.google.instrumentation.tags;
 import com.google.instrumentation.internal.StringUtil;
 import javax.annotation.Nullable;
 
-/** A set of tags. */
+/**
+ * A set of key-value pairs that can be used to label anything that is associated with a specific
+ * operation.
+ *
+ * <p>For example, {@code TagSet}s can be used to label stats, log messages, or debugging
+ * information.
+ */
 public abstract class TagSet {
   /** The maximum length for a string tag value. */
   public static final int MAX_STRING_LENGTH = StringUtil.MAX_LENGTH;