diff --git a/REFERENCE.md b/REFERENCE.md
index ad70e212..320f12f8 100644
--- a/REFERENCE.md
+++ b/REFERENCE.md
@@ -64,8 +64,7 @@
 
 ### <a name="puppet_agent"></a>`puppet_agent`
 
-example for clients in dmz:s that need to use proxy to reach the repo
-  provided by puppetserver.
+Upgrades Puppet 4 and newer to the requested version.
 
 #### Parameters
 
@@ -343,6 +342,8 @@ Default value: `[]`
 Data type: `Optional`
 
 This is to be able to configure yum-repo with proxy, needed for
+example for clients in DMZs that need to use proxy to reach the repo
+provided by puppetserver.
 
 Default value: `undef`
 
@@ -388,15 +389,15 @@ The following parameters are available in the `puppet_agent::install` class:
 
 ##### <a name="-puppet_agent--install--package_version"></a>`package_version`
 
-Data type: `String`
+Data type: `Optional[String]`
 
 The puppet-agent version to install.
 
-Default value: `'present'`
+Default value: `undef`
 
 ##### <a name="-puppet_agent--install--install_dir"></a>`install_dir`
 
-Data type: `Optional`
+Data type: `Optional[[Stdlib::Absolutepath]]`
 
 The directory the puppet agent should be installed to. This is only applicable for
 windows operating systems.
@@ -405,7 +406,7 @@ Default value: `undef`
 
 ##### <a name="-puppet_agent--install--install_options"></a>`install_options`
 
-Data type: `Array`
+Data type: `Optional[Array]`
 
 An array of additional options to pass when installing puppet-agent. Each option in
 the array can either be a string or a hash. Each option will automatically be quoted
@@ -415,7 +416,7 @@ the installation command, forward slashes won't be automatically converted like
 are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 be escaped and backslashes in single-quoted strings _can_ be escaped.
 
-Default value: `[]`
+Default value: `undef`
 
 ### <a name="puppet_agent--install--darwin"></a>`puppet_agent::install::darwin`
 
@@ -430,13 +431,13 @@ The following parameters are available in the `puppet_agent::install::darwin` cl
 
 ##### <a name="-puppet_agent--install--darwin--package_version"></a>`package_version`
 
-Data type: `Optional`
+Data type: `String`
 
 The puppet-agent version to install.
 
 ##### <a name="-puppet_agent--install--darwin--install_options"></a>`install_options`
 
-Data type: `Array`
+Data type: `Optional[Array]`
 
 An array of additional options to pass when installing puppet-agent. Each option in
 the array can either be a string or a hash. Each option will automatically be quoted
@@ -446,7 +447,7 @@ the installation command, forward slashes won't be automatically converted like
 are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 be escaped and backslashes in single-quoted strings _can_ be escaped.
 
-Default value: `[]`
+Default value: `undef`
 
 ### <a name="puppet_agent--install--solaris"></a>`puppet_agent::install::solaris`
 
@@ -461,13 +462,13 @@ The following parameters are available in the `puppet_agent::install::solaris` c
 
 ##### <a name="-puppet_agent--install--solaris--package_version"></a>`package_version`
 
-Data type: `Optional`
+Data type: `String`
 
 The puppet-agent version to install.
 
 ##### <a name="-puppet_agent--install--solaris--install_options"></a>`install_options`
 
-Data type: `Array`
+Data type: `Optional[Array]`
 
 An array of additional options to pass when installing puppet-agent. Each option in
 the array can either be a string or a hash. Each option will automatically be quoted
@@ -477,7 +478,7 @@ the installation command, forward slashes won't be automatically converted like
 are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 be escaped and backslashes in single-quoted strings _can_ be escaped.
 
-Default value: `[]`
+Default value: `undef`
 
 ### <a name="puppet_agent--install--suse"></a>`puppet_agent::install::suse`
 
@@ -492,13 +493,13 @@ The following parameters are available in the `puppet_agent::install::suse` clas
 
 ##### <a name="-puppet_agent--install--suse--package_version"></a>`package_version`
 
-Data type: `Optional`
+Data type: `String`
 
 The puppet-agent version to install.
 
 ##### <a name="-puppet_agent--install--suse--install_options"></a>`install_options`
 
-Data type: `Array`
+Data type: `Optional[Array]`
 
 An array of additional options to pass when installing puppet-agent.
 Each option in the array can either be a string or a hash.
@@ -509,7 +510,7 @@ command, forward slashes won't be automatically converted like they are in
 `file` resources.) Note also that backslashes in double-quoted strings
 _must_ be escaped and backslashes in single-quoted strings _can_ be escaped.
 
-Default value: `[]`
+Default value: `undef`
 
 ### <a name="puppet_agent--install--windows"></a>`puppet_agent::install::windows`
 
@@ -608,9 +609,10 @@ The following parameters are available in the `puppet_agent::prepare::package` c
 
 ##### <a name="-puppet_agent--prepare--package--source"></a>`source`
 
-Data type: `Optional`
-
+Data type: `Variant[String, Array]`
 
+The source file for the puppet-agent package. Can use any of the data types
+and protocols that the File resource's source attribute can.
 
 ### <a name="puppet_agent--prepare--puppet_config"></a>`puppet_agent::prepare::puppet_config`
 
@@ -624,7 +626,7 @@ The following parameters are available in the `puppet_agent::prepare::puppet_con
 
 ##### <a name="-puppet_agent--prepare--puppet_config--package_version"></a>`package_version`
 
-Data type: `Optional`
+Data type: `String`
 
 The puppet-agent version to install.
 
diff --git a/manifests/init.pp b/manifests/init.pp
index 0266d192..4495bba4 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -95,8 +95,8 @@
 #   This parameter is constrained to managing only a predetermined set of configuration
 #   settings, e.g. runinterval.
 # @param proxy
-#    This is to be able to configure yum-repo with proxy, needed for
-#   example for clients in dmz:s that need to use proxy to reach the repo
+#   This is to be able to configure yum-repo with proxy, needed for
+#   example for clients in DMZs that need to use proxy to reach the repo
 #   provided by puppetserver.
 # @param version_file_path
 #    The default install path for the VERSION file
diff --git a/manifests/install.pp b/manifests/install.pp
index 8bb6d43a..ba7af90d 100644
--- a/manifests/install.pp
+++ b/manifests/install.pp
@@ -14,9 +14,9 @@
 #   are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 #   be escaped and backslashes in single-quoted strings _can_ be escaped.
 class puppet_agent::install (
-  String   $package_version = 'present',
-  Optional $install_dir     = undef,
-  Array    $install_options = [],
+  Optional[String]                 $package_version = undef,
+  Optional[[Stdlib::Absolutepath]] $install_dir     = undef,
+  Optional[Array]                  $install_options = undef,
 ) {
   assert_private()
 
diff --git a/manifests/install/darwin.pp b/manifests/install/darwin.pp
index ad38da9b..912ab4ae 100644
--- a/manifests/install/darwin.pp
+++ b/manifests/install/darwin.pp
@@ -12,8 +12,8 @@
 #   are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 #   be escaped and backslashes in single-quoted strings _can_ be escaped.
 class puppet_agent::install::darwin (
-  Optional $package_version,
-  Array    $install_options = [],
+  String          $package_version,
+  Optional[Array] $install_options = undef,
 ) {
   assert_private()
   $install_script = 'osx_install.sh.erb'
diff --git a/manifests/install/solaris.pp b/manifests/install/solaris.pp
index eedd75e3..e8bc513f 100644
--- a/manifests/install/solaris.pp
+++ b/manifests/install/solaris.pp
@@ -12,8 +12,8 @@
 #   are in `file` resources.) Note also that backslashes in double-quoted strings _must_
 #   be escaped and backslashes in single-quoted strings _can_ be escaped.
 class puppet_agent::install::solaris (
-  Optional $package_version,
-  Array    $install_options = [],
+  String          $package_version,
+  Optional[Array] $install_options = undef,
 ) {
   assert_private()
   if $facts['os']['release']['major'] == '10' {
diff --git a/manifests/install/suse.pp b/manifests/install/suse.pp
index 73a04c00..9769ed6b 100644
--- a/manifests/install/suse.pp
+++ b/manifests/install/suse.pp
@@ -13,8 +13,8 @@
 #   `file` resources.) Note also that backslashes in double-quoted strings
 #   _must_ be escaped and backslashes in single-quoted strings _can_ be escaped.
 class puppet_agent::install::suse (
-  Optional $package_version,
-  Array    $install_options = [],
+  String          $package_version,
+  Optional[Array] $install_options = undef,
 ) {
   assert_private()
 
diff --git a/manifests/prepare/package.pp b/manifests/prepare/package.pp
index 0d649a9d..5711e2d7 100644
--- a/manifests/prepare/package.pp
+++ b/manifests/prepare/package.pp
@@ -3,8 +3,10 @@
 # working with a remote https repository.
 #
 # @param source
+#   The source file for the puppet-agent package. Can use any of the data types
+#   and protocols that the File resource's source attribute can.
 class puppet_agent::prepare::package (
-  Optional $source,
+  Variant[String, Array] $source,
 ) {
   assert_private()
 
diff --git a/manifests/prepare/puppet_config.pp b/manifests/prepare/puppet_config.pp
index 74bc68fc..5ba4d35e 100644
--- a/manifests/prepare/puppet_config.pp
+++ b/manifests/prepare/puppet_config.pp
@@ -3,7 +3,7 @@
 # @param package_version
 #   The puppet-agent version to install.
 class puppet_agent::prepare::puppet_config (
-  Optional $package_version,
+  String $package_version,
 ) {
   assert_private()
   $puppetconf = $puppet_agent::params::config