diff --git a/conf/nutch-default.xml b/conf/nutch-default.xml
index 273cfccc57..084ad86d07 100644
--- a/conf/nutch-default.xml
+++ b/conf/nutch-default.xml
@@ -72,9 +72,18 @@
 <property>
   <name>http.agent.name</name>
   <value></value>
-  <description>HTTP 'User-Agent' request header. MUST NOT be empty -
+  <description>'User-Agent' name: a single word uniquely identifying your crawler.
+
+  The value is used to select the group of robots.txt rules addressing your
+  crawler. It is also sent as part of the HTTP 'User-Agent' request header.
+
+  This property MUST NOT be empty -
   please set this to a single word uniquely related to your organization.
 
+  Following RFC 9309 the 'User-Agent' name (aka. 'product token')
+  &quot;MUST contain only uppercase and lowercase letters ('a-z' and
+  'A-Z'), underscores ('_'), and hyphens ('-').&quot;
+
   NOTE: You should also check other related properties:
 
     http.robots.agents
@@ -84,7 +93,6 @@
     http.agent.version
 
   and set their values appropriately.
-
   </description>
 </property>
 
@@ -95,13 +103,13 @@
   parser would look for in robots.txt. Multiple agents can be provided using
   comma as a delimiter. eg. mybot,foo-spider,bar-crawler
 
-  The ordering of agents does NOT matter and the robots parser would make
-  decision based on the agent which matches first to the robots rules.
-  Also, there is NO need to add a wildcard (ie. "*") to this string as the
-  robots parser would smartly take care of a no-match situation.
+  The ordering of agents does NOT matter and the robots.txt parser combines
+  all rules to any of the agent names.  Also, there is NO need to add
+  a wildcard (ie. "*") to this string as the robots parser would smartly
+  take care of a no-match situation.
 
   If no value is specified, by default HTTP agent (ie. 'http.agent.name')
-  would be used for user agent matching by the robots parser.
+  is used for user-agent matching by the robots parser.
   </description>
 </property>
 
@@ -166,9 +174,9 @@
 <property>
   <name>http.agent.url</name>
   <value></value>
-  <description>A URL to advertise in the User-Agent header.  This will
+  <description>A URL to advertise in the User-Agent header. This will
    appear in parenthesis after the agent name. Custom dictates that this
-   should be a URL of a page explaining the purpose and behavior of this
+   should be a URL to a page that explains the purpose and behavior of this
    crawler.
   </description>
 </property>
@@ -176,9 +184,9 @@
 <property>
   <name>http.agent.email</name>
   <value></value>
-  <description>An email address to advertise in the HTTP 'From' request
-   header and User-Agent header. A good practice is to mangle this
-   address (e.g. 'info at example dot com') to avoid spamming.
+  <description>An email address to advertise in the HTTP 'User-Agent' (and
+   'From') request headers. A good practice is to mangle this address
+   (e.g. 'info at example dot com') to avoid spamming.
   </description>
 </property>
 
@@ -202,7 +210,7 @@
   <name>http.agent.rotate.file</name>
   <value>agents.txt</value>
   <description>
-    File containing alternative user agent names to be used instead of
+    File containing alternative user-agent names to be used instead of
     http.agent.name on a rotating basis if http.agent.rotate is true.
     Each line of the file should contain exactly one agent
     specification including name, version, description, URL, etc.