diff --git a/include/curl_wrapper.hpp b/include/curl_wrapper.hpp
index 890b36e..bd443ed 100644
--- a/include/curl_wrapper.hpp
+++ b/include/curl_wrapper.hpp
@@ -239,6 +239,11 @@ protected:
      */
     void set_cainfo(string_view path);
 
+    /*!
+     *  @brief  Sets the User-Agent.
+     *
+     *  @since  0.3.0
+     */
     void set_useragent(string_view useragent);
 
 private:
diff --git a/include/instance.hpp b/include/instance.hpp
index 8f17525..009c308 100644
--- a/include/instance.hpp
+++ b/include/instance.hpp
@@ -189,6 +189,14 @@ public:
         CURLWrapper::set_cainfo(path);
     }
 
+    /*!
+     *  @brief  Sets the User-Agent.
+     *
+     *  Sets also the User-Agent for all Connection%s that are initialized with
+     *  this Instance afterwards.
+     *
+     *  @since  0.3.0
+     */
     void set_useragent(const string_view useragent)
     {
         _useragent = useragent;
@@ -226,6 +234,11 @@ public:
     class ObtainToken : public CURLWrapper
     {
     public:
+        /*!
+         *  @brief  Constructor.
+         *
+         *  @since  0.3.0
+         */
         explicit ObtainToken(Instance &instance)
             : _instance{instance}
             , _baseuri{instance.get_baseuri()}