diff --git a/analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/annotations/AnnotationsProvider.kt b/analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/annotations/AnnotationsProvider.kt
index 078043d6bf7..32a5399e700 100644
--- a/analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/annotations/AnnotationsProvider.kt
+++ b/analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/annotations/AnnotationsProvider.kt
@@ -7,11 +7,37 @@ package org.jetbrains.kotlin.light.classes.symbol.annotations
 
 import org.jetbrains.kotlin.analysis.api.annotations.KtAnnotationApplicationInfo
 import org.jetbrains.kotlin.analysis.api.annotations.KtAnnotationApplicationWithArgumentsInfo
+import org.jetbrains.kotlin.analysis.api.symbols.markers.KtAnnotatedSymbol
 import org.jetbrains.kotlin.name.ClassId
 
+/**
+ * This class provides annotations to [LazyAnnotationsBox].
+ *
+ * [EmptyAnnotationsProvider] is just an empty provider.
+ * [SymbolAnnotationsProvider] is a provider based on [KtAnnotatedSymbol] API.
+ * [CompositeAnnotationsProvider] is a composition of some [AnnotationsProvider].
+ *
+ * @see [LazyAnnotationsBox]
+ */
 internal sealed interface AnnotationsProvider {
+    /**
+     * @return a list of [KtAnnotationApplicationInfo] applicable for this provider
+     */
     fun annotationInfos(): List<KtAnnotationApplicationInfo>
     operator fun get(classId: ClassId): Collection<KtAnnotationApplicationWithArgumentsInfo>
     operator fun contains(classId: ClassId): Boolean
+
+    /**
+     * Example:
+     * ```
+     * package one
+     *
+     * @Ann1 @Ann2
+     * class Foo
+     * ```
+     * If this provider provides annotations from `Foo` class then the result of the function will be [ClassId] for `one.Foo`
+     *
+     * @return [ClassId] of an owner of annotations from this provider
+     */
     fun ownerClassId(): ClassId?
 }