diff --git a/src/Enclave.Sdk/Clients/AuthorityClient.cs b/src/Enclave.Sdk/Clients/AuthorityClient.cs
deleted file mode 100644
index ec19132..0000000
--- a/src/Enclave.Sdk/Clients/AuthorityClient.cs
+++ /dev/null
@@ -1,14 +0,0 @@
-using Enclave.Sdk.Api.Clients.Interfaces;
-
-namespace Enclave.Sdk.Api.Clients;
-
-internal class AuthorityClient : ClientBase, IAuthorityClient
-{
-    private readonly string _orgRoute;
-
-    public AuthorityClient(HttpClient httpClient, string orgRoute)
-    : base(httpClient)
-    {
-        _orgRoute = orgRoute;
-    }
-}
diff --git a/src/Enclave.Sdk/Clients/ClientBase.cs b/src/Enclave.Sdk/Clients/ClientBase.cs
index 64f5a21..3fafe03 100644
--- a/src/Enclave.Sdk/Clients/ClientBase.cs
+++ b/src/Enclave.Sdk/Clients/ClientBase.cs
@@ -32,7 +32,7 @@ protected ClientBase(HttpClient httpClient)
     /// <param name="data">the object to encode.</param>
     /// <returns>String content of object.</returns>
     /// <exception cref="ArgumentNullException">throws if data provided is null.</exception>
-    protected StringContent CreateJsonContent<TModel>(TModel data)
+    protected static StringContent CreateJsonContent<TModel>(TModel data)
     {
         if (data is null)
         {
@@ -51,7 +51,7 @@ protected StringContent CreateJsonContent<TModel>(TModel data)
     /// <typeparam name="TModel">the object type to deserialise to.</typeparam>
     /// <param name="httpContent">httpContent from the API call.</param>
     /// <returns>the object of type specified.</returns>
-    protected async Task<TModel?> DeserialiseAsync<TModel>(HttpContent httpContent)
+    protected static async Task<TModel?> DeserialiseAsync<TModel>(HttpContent httpContent)
     {
         if (httpContent is null)
         {
diff --git a/src/Enclave.Sdk/Clients/Interfaces/IAuthorityClient.cs b/src/Enclave.Sdk/Clients/Interfaces/IAuthorityClient.cs
deleted file mode 100644
index 49b89d6..0000000
--- a/src/Enclave.Sdk/Clients/Interfaces/IAuthorityClient.cs
+++ /dev/null
@@ -1,5 +0,0 @@
-namespace Enclave.Sdk.Api.Clients.Interfaces;
-
-public interface IAuthorityClient
-{
-}
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Clients/Interfaces/IDnsClient.cs b/src/Enclave.Sdk/Clients/Interfaces/IDnsClient.cs
index 0082f1c..ddedbcc 100644
--- a/src/Enclave.Sdk/Clients/Interfaces/IDnsClient.cs
+++ b/src/Enclave.Sdk/Clients/Interfaces/IDnsClient.cs
@@ -70,7 +70,7 @@ Task<PaginatedResponseModel<DnsRecordSummary>> GetRecordsAsync(
     /// <summary>
     /// Create a DNS Record using a <see cref="DnsRecordCreate"/> model.
     /// </summary>
-    /// <param name="createModel">The model needed to create a DNS Record</param>
+    /// <param name="createModel">The model needed to create a DNS Record.</param>
     /// <returns>The created DNS Record as <see cref="DnsRecordCreate"/>.</returns>
     Task<DnsRecord> CreateRecordAsync(DnsRecordCreate createModel);
 
@@ -92,7 +92,7 @@ Task<PaginatedResponseModel<DnsRecordSummary>> GetRecordsAsync(
     /// Get a detailed DNS Record.
     /// </summary>
     /// <param name="dnsRecordId">The id of the DNS Record you want to get.</param>
-    /// <returns>A detailed DNS Record object</returns>
+    /// <returns>A detailed DNS Record object.</returns>
     Task<DnsRecord> GetRecordAsync(DnsRecordId dnsRecordId);
 
     /// <summary>
diff --git a/src/Enclave.Sdk/Clients/Interfaces/IOrganisationClient.cs b/src/Enclave.Sdk/Clients/Interfaces/IOrganisationClient.cs
index ee9f6be..5cff80b 100644
--- a/src/Enclave.Sdk/Clients/Interfaces/IOrganisationClient.cs
+++ b/src/Enclave.Sdk/Clients/Interfaces/IOrganisationClient.cs
@@ -16,11 +16,6 @@ public interface IOrganisationClient
     /// </summary>
     AccountOrganisation Organisation { get; }
 
-    /// <summary>
-    /// An instance of <see cref="AuthorityClient"/> associated with the current organisaiton.
-    /// </summary>
-    IAuthorityClient Authority { get; }
-
     /// <summary>
     /// An instance of <see cref="DnsClient"/> associated with the current organisaiton.
     /// </summary>
diff --git a/src/Enclave.Sdk/Clients/OrganisationClient.cs b/src/Enclave.Sdk/Clients/OrganisationClient.cs
index 3955e48..2a10d30 100644
--- a/src/Enclave.Sdk/Clients/OrganisationClient.cs
+++ b/src/Enclave.Sdk/Clients/OrganisationClient.cs
@@ -24,19 +24,18 @@ public OrganisationClient(HttpClient httpClient, AccountOrganisation currentOrga
         Organisation = currentOrganisation;
         _orgRoute = $"org/{Organisation.OrgId}";
 
-        EnrolmentKeys = new EnrolmentKeysClient(httpClient, _orgRoute);
         Dns = new DnsClient(httpClient, _orgRoute);
-        UnapprovedSystems = new UnapprovedSystemsClient(httpClient, _orgRoute);
-        EnrolledSystems = new EnrolledSystemsClient(httpClient, _orgRoute);
+        EnrolmentKeys = new EnrolmentKeysClient(httpClient, _orgRoute);
+        Logs = new LogsClient(httpClient, _orgRoute);
         Policies = new PoliciesClient(httpClient, _orgRoute);
+        EnrolledSystems = new EnrolledSystemsClient(httpClient, _orgRoute);
+        Tags = new TagsClient(httpClient, _orgRoute);
+        UnapprovedSystems = new UnapprovedSystemsClient(httpClient, _orgRoute);
     }
 
     /// <inheritdoc/>
     public AccountOrganisation Organisation { get; }
 
-    /// <inheritdoc/>
-    public IAuthorityClient Authority => throw new NotImplementedException();
-
     /// <inheritdoc/>
     public IDnsClient Dns { get; }
 
@@ -44,7 +43,7 @@ public OrganisationClient(HttpClient httpClient, AccountOrganisation currentOrga
     public IEnrolmentKeysClient EnrolmentKeys { get; }
 
     /// <inheritdoc/>
-    public ILogsClient Logs => throw new NotImplementedException();
+    public ILogsClient Logs { get; }
 
     /// <inheritdoc/>
     public IPoliciesClient Policies { get; }
@@ -53,7 +52,7 @@ public OrganisationClient(HttpClient httpClient, AccountOrganisation currentOrga
     public IEnrolledSystemsClient EnrolledSystems { get; }
 
     /// <inheritdoc/>
-    public ITagsClient Tags => throw new NotImplementedException();
+    public ITagsClient Tags { get; }
 
     /// <inheritdoc/>
     public IUnapprovedSystemsClient UnapprovedSystems { get; }
diff --git a/src/Enclave.Sdk/Constants.cs b/src/Enclave.Sdk/Constants.cs
index 38af783..5373998 100644
--- a/src/Enclave.Sdk/Constants.cs
+++ b/src/Enclave.Sdk/Constants.cs
@@ -9,7 +9,6 @@ public static JsonSerializerOptions JsonSerializerOptions
     {
         get
         {
-
             var options = new JsonSerializerOptions
             {
                 PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
diff --git a/src/Enclave.Sdk/Data/Account/UserOrganisationRole.cs b/src/Enclave.Sdk/Data/Account/UserOrganisationRole.cs
index d5af46d..72fcb83 100644
--- a/src/Enclave.Sdk/Data/Account/UserOrganisationRole.cs
+++ b/src/Enclave.Sdk/Data/Account/UserOrganisationRole.cs
@@ -1,7 +1,17 @@
 namespace Enclave.Sdk.Api.Data.Account;
 
+/// <summary>
+/// The User roles.
+/// </summary>
 public enum UserOrganisationRole
 {
+    /// <summary>
+    /// The owner of the organisation.
+    /// </summary>
     Owner,
+
+    /// <summary>
+    /// An Admin of the organisaiton.
+    /// </summary>
     Admin,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Dns/DnsRecord.cs b/src/Enclave.Sdk/Data/Dns/DnsRecord.cs
index cba7800..a07e456 100644
--- a/src/Enclave.Sdk/Data/Dns/DnsRecord.cs
+++ b/src/Enclave.Sdk/Data/Dns/DnsRecord.cs
@@ -9,7 +9,6 @@ namespace Enclave.Sdk.Api.Data.Dns;
 /// </summary>
 public class DnsRecord
 {
-
     /// <summary>
     /// The ID of the record.
     /// </summary>
diff --git a/src/Enclave.Sdk/Data/Dns/DnsRecordId.cs b/src/Enclave.Sdk/Data/Dns/DnsRecordId.cs
index 0982fb0..12423c4 100644
--- a/src/Enclave.Sdk/Data/Dns/DnsRecordId.cs
+++ b/src/Enclave.Sdk/Data/Dns/DnsRecordId.cs
@@ -2,6 +2,9 @@
 
 namespace Enclave.Sdk.Api.Data.Dns;
 
+/// <summary>
+/// An int backed Dns Record Id.
+/// </summary>
 [TypedId(IdBackingType.Int)]
 public readonly partial struct DnsRecordId
 {
diff --git a/src/Enclave.Sdk/Data/Dns/DnsZoneId.cs b/src/Enclave.Sdk/Data/Dns/DnsZoneId.cs
index 17694d4..19a491a 100644
--- a/src/Enclave.Sdk/Data/Dns/DnsZoneId.cs
+++ b/src/Enclave.Sdk/Data/Dns/DnsZoneId.cs
@@ -2,6 +2,9 @@
 
 namespace Enclave.Sdk.Api.Data.Dns;
 
+/// <summary>
+/// An int backed Dns Zone Id.
+/// </summary>
 [TypedId(IdBackingType.Int)]
 public readonly partial struct DnsZoneId
 {
diff --git a/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemQuerySortMode.cs b/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemQuerySortMode.cs
index 60b233f..9864272 100644
--- a/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemQuerySortMode.cs
+++ b/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemQuerySortMode.cs
@@ -1,9 +1,27 @@
 namespace Enclave.Sdk.Api.Data.EnrolledSystems.Enum;
 
+/// <summary>
+/// System Query Sort order used when making a System request.
+/// </summary>
 public enum SystemQuerySortMode
 {
+    /// <summary>
+    /// Sort by recently enrolled.
+    /// </summary>
     RecentlyEnrolled,
+
+    /// <summary>
+    /// Sort by recently connected.
+    /// </summary>
     RecentlyConnected,
+
+    /// <summary>
+    /// Sort by description.
+    /// </summary>
     Description,
+
+    /// <summary>
+    /// Sort by enrolment key.
+    /// </summary>
     EnrolmentKeyUsed,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemType.cs b/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemType.cs
index 8af7fbc..bce91a5 100644
--- a/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemType.cs
+++ b/src/Enclave.Sdk/Data/EnrolledSystems/Enum/SystemType.cs
@@ -1,7 +1,19 @@
 namespace Enclave.Sdk.Api.Data.EnrolledSystems.Enum;
 
+/// <summary>
+/// Defines the types of Systems.
+/// </summary>
 public enum SystemType
 {
+    /// <summary>
+    /// For workstations, laptops, servers, and other systems that are relatively long-lived or manually provisioned.
+    /// Systems remain in your Enclave Organisation if they stop running.
+    /// </summary>
     GeneralPurpose,
+
+    /// <summary>
+    /// For containers, kubernetes pods, and other systems that are temporary, short-lived or automatically provisioned.
+    /// Systems are automatically removed from your Enclave Organisation when they stop/disconnect.
+    /// </summary>
     Ephemeral,
 }
diff --git a/src/Enclave.Sdk/Data/EnrolmentKeys/EnrolmentKeyId.cs b/src/Enclave.Sdk/Data/EnrolmentKeys/EnrolmentKeyId.cs
index c651970..d26a553 100644
--- a/src/Enclave.Sdk/Data/EnrolmentKeys/EnrolmentKeyId.cs
+++ b/src/Enclave.Sdk/Data/EnrolmentKeys/EnrolmentKeyId.cs
@@ -2,6 +2,9 @@
 
 namespace Enclave.Sdk.Api.Data.EnrolmentKeys;
 
+/// <summary>
+/// An int backed Enrolment Key Id.
+/// </summary>
 [TypedId(IdBackingType.Int)]
 public partial struct EnrolmentKeyId
 {
diff --git a/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/ApprovalMode.cs b/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/ApprovalMode.cs
index bf1ddad..8c3b64c 100644
--- a/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/ApprovalMode.cs
+++ b/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/ApprovalMode.cs
@@ -1,7 +1,17 @@
 namespace Enclave.Sdk.Api.Data.EnrolmentKeys.Enum;
 
+/// <summary>
+/// System Approval Mode.
+/// </summary>
 public enum ApprovalMode
 {
+    /// <summary>
+    /// Automatically approve systems.
+    /// </summary>
     Automatic,
+
+    /// <summary>
+    /// Manually approve systems.
+    /// </summary>
     Manual,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/EnrolmentKeySortOrder.cs b/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/EnrolmentKeySortOrder.cs
index 0da202c..fa62bef 100644
--- a/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/EnrolmentKeySortOrder.cs
+++ b/src/Enclave.Sdk/Data/EnrolmentKeys/Enum/EnrolmentKeySortOrder.cs
@@ -1,9 +1,27 @@
 namespace Enclave.Sdk.Api.Data.EnrolmentKeys.Enum;
 
+/// <summary>
+/// Enrolment Key Sort Order used when making an Enrolment Key request.
+/// </summary>
 public enum EnrolmentKeySortOrder
 {
+    /// <summary>
+    /// Sort by Description.
+    /// </summary>
     Description,
+
+    /// <summary>
+    /// Sort by Last Used.
+    /// </summary>
     LastUsed,
+
+    /// <summary>
+    /// Sort By Approval Mode.
+    /// </summary>
     ApprovalMode,
+
+    /// <summary>
+    /// Sort by Uses Remaining.
+    /// </summary>
     UsesRemaining,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Logging/Enum/ActivityLogLevel.cs b/src/Enclave.Sdk/Data/Logging/Enum/ActivityLogLevel.cs
index 70f0bd2..11b52d6 100644
--- a/src/Enclave.Sdk/Data/Logging/Enum/ActivityLogLevel.cs
+++ b/src/Enclave.Sdk/Data/Logging/Enum/ActivityLogLevel.cs
@@ -1,8 +1,22 @@
 namespace Enclave.Sdk.Api.Data.Logging.Enum;
 
+/// <summary>
+/// Log Error Type.
+/// </summary>
 public enum ActivityLogLevel
 {
+    /// <summary>
+    /// Information log level.
+    /// </summary>
     Information,
+
+    /// <summary>
+    /// Warning Log.
+    /// </summary>
     Warning,
+
+    /// <summary>
+    /// Error Log.
+    /// </summary>
     Error,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Organisations/Enum/OrganisationPlan.cs b/src/Enclave.Sdk/Data/Organisations/Enum/OrganisationPlan.cs
index 8ed8025..c845afa 100644
--- a/src/Enclave.Sdk/Data/Organisations/Enum/OrganisationPlan.cs
+++ b/src/Enclave.Sdk/Data/Organisations/Enum/OrganisationPlan.cs
@@ -1,8 +1,22 @@
 namespace Enclave.Sdk.Api.Data.Organisations.Enum;
 
+/// <summary>
+/// An Enum describing the types of plan.
+/// </summary>
 public enum OrganisationPlan
 {
+    /// <summary>
+    /// Starter Organisation Plan.
+    /// </summary>
     Starter = 0,
+
+    /// <summary>
+    /// Pro Organisaiton Plan.
+    /// </summary>
     Pro = 1,
+
+    /// <summary>
+    /// Business Organisaiton Plan.
+    /// </summary>
     Business = 2,
 }
diff --git a/src/Enclave.Sdk/Data/Organisations/OrganisationUser.cs b/src/Enclave.Sdk/Data/Organisations/OrganisationUser.cs
index 59b7519..03c2f41 100644
--- a/src/Enclave.Sdk/Data/Organisations/OrganisationUser.cs
+++ b/src/Enclave.Sdk/Data/Organisations/OrganisationUser.cs
@@ -38,7 +38,13 @@ public class OrganisationUser
     public UserOrganisationRole Role { get; init; }
 }
 
+/// <summary>
+/// Top Level model for organisation user requests.
+/// </summary>
 public class OrganisationUsersTopLevel
 {
+    /// <summary>
+    /// A list of Organisation Users.
+    /// </summary>
     public IReadOnlyList<OrganisationUser>? Users { get; init; }
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Pagination/PaginatedResponseModel.cs b/src/Enclave.Sdk/Data/Pagination/PaginatedResponseModel.cs
index 6018bb9..17e9de4 100644
--- a/src/Enclave.Sdk/Data/Pagination/PaginatedResponseModel.cs
+++ b/src/Enclave.Sdk/Data/Pagination/PaginatedResponseModel.cs
@@ -9,15 +9,15 @@ public class PaginatedResponseModel<TItemType>
     /// <summary>
     /// Metadata for the paginated data.
     /// </summary>
-    public PaginationMetadata Metadata { get; init; }
+    public PaginationMetadata Metadata { get; init; } = default!;
 
     /// <summary>
     /// The related links for the current page of data.
     /// </summary>
-    public PaginationLinks Links { get; init; }
+    public PaginationLinks Links { get; init; } = default!;
 
     /// <summary>
     /// The requested page of items.
     /// </summary>
-    public IEnumerable<TItemType> Items { get; init; }
+    public IEnumerable<TItemType> Items { get; init; } = default!;
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Pagination/PaginationLinks.cs b/src/Enclave.Sdk/Data/Pagination/PaginationLinks.cs
index d72c346..4445eae 100644
--- a/src/Enclave.Sdk/Data/Pagination/PaginationLinks.cs
+++ b/src/Enclave.Sdk/Data/Pagination/PaginationLinks.cs
@@ -8,7 +8,7 @@ public class PaginationLinks
     /// <summary>
     /// The first page of data.
     /// </summary>
-    public Uri First { get; init; }
+    public Uri? First { get; init; }
 
     /// <summary>
     /// The previous page of data (or null if this is the first page).
@@ -23,5 +23,5 @@ public class PaginationLinks
     /// <summary>
     /// The last page of data.
     /// </summary>
-    public Uri Last { get; init; }
+    public Uri? Last { get; init; }
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/PatchModel/IPatchModel.cs b/src/Enclave.Sdk/Data/PatchModel/IPatchModel.cs
index 96e0059..2b3f768 100644
--- a/src/Enclave.Sdk/Data/PatchModel/IPatchModel.cs
+++ b/src/Enclave.Sdk/Data/PatchModel/IPatchModel.cs
@@ -1,5 +1,9 @@
 namespace Enclave.Sdk.Api.Data.PatchModel;
 
+/// <summary>
+/// An interface for use with a PatchBuilder.
+/// </summary>
+[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1040:Avoid empty interfaces", Justification = "Useful for using PatchBuilder")]
 public interface IPatchModel
 {
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Policies/Enum/PolicyAclProtocol.cs b/src/Enclave.Sdk/Data/Policies/Enum/PolicyAclProtocol.cs
index 880fb8a..a4d7bed 100644
--- a/src/Enclave.Sdk/Data/Policies/Enum/PolicyAclProtocol.cs
+++ b/src/Enclave.Sdk/Data/Policies/Enum/PolicyAclProtocol.cs
@@ -5,8 +5,23 @@
 /// </summary>
 public enum PolicyAclProtocol
 {
+    /// <summary>
+    /// Any Protocol.
+    /// </summary>
     Any,
+
+    /// <summary>
+    /// Tcp.
+    /// </summary>
     Tcp,
+
+    /// <summary>
+    /// Udp.
+    /// </summary>
     Udp,
+
+    /// <summary>
+    /// Icmp.
+    /// </summary>
     Icmp,
 }
diff --git a/src/Enclave.Sdk/Data/Policies/Enum/PolicySortOrder.cs b/src/Enclave.Sdk/Data/Policies/Enum/PolicySortOrder.cs
index c6ad0d1..c46565d 100644
--- a/src/Enclave.Sdk/Data/Policies/Enum/PolicySortOrder.cs
+++ b/src/Enclave.Sdk/Data/Policies/Enum/PolicySortOrder.cs
@@ -1,7 +1,17 @@
 namespace Enclave.Sdk.Api.Data.Policies.Enum;
 
+/// <summary>
+/// The sort order when making a Policy Request.
+/// </summary>
 public enum PolicySortOrder
 {
+    /// <summary>
+    /// Sort by description.
+    /// </summary>
     Description,
+
+    /// <summary>
+    /// Sort by recently created.
+    /// </summary>
     RecentlyCreated,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/Policies/PolicyId.cs b/src/Enclave.Sdk/Data/Policies/PolicyId.cs
index ecd7df8..6f8e191 100644
--- a/src/Enclave.Sdk/Data/Policies/PolicyId.cs
+++ b/src/Enclave.Sdk/Data/Policies/PolicyId.cs
@@ -2,6 +2,9 @@
 
 namespace Enclave.Sdk.Api.Data.Policies;
 
+/// <summary>
+/// An int backed Policy Id.
+/// </summary>
 [TypedId(IdBackingType.Int)]
 public partial struct PolicyId
 {
diff --git a/src/Enclave.Sdk/Data/SystemId.cs b/src/Enclave.Sdk/Data/SystemId.cs
index dafd624..4156752 100644
--- a/src/Enclave.Sdk/Data/SystemId.cs
+++ b/src/Enclave.Sdk/Data/SystemId.cs
@@ -2,6 +2,9 @@
 
 namespace Enclave.Sdk.Api.Data;
 
+/// <summary>
+/// A String backed System Id.
+/// </summary>
 [TypedId(IdBackingType.String)]
 public partial struct SystemId
 {
diff --git a/src/Enclave.Sdk/Data/SystemManagement/SystemReference.cs b/src/Enclave.Sdk/Data/SystemManagement/SystemReference.cs
index b2eb874..fa24d19 100644
--- a/src/Enclave.Sdk/Data/SystemManagement/SystemReference.cs
+++ b/src/Enclave.Sdk/Data/SystemManagement/SystemReference.cs
@@ -15,7 +15,7 @@ public class SystemReference
     /// <summary>
     /// The System ID.
     /// </summary>
-    public string Id { get; init; }
+    public string Id { get; init; } = default!;
 
     /// <summary>
     /// The local hostname of the system (if known).
diff --git a/src/Enclave.Sdk/Data/Tags/TagQuerySortOrder.cs b/src/Enclave.Sdk/Data/Tags/TagQuerySortOrder.cs
index d44057f..13c6d99 100644
--- a/src/Enclave.Sdk/Data/Tags/TagQuerySortOrder.cs
+++ b/src/Enclave.Sdk/Data/Tags/TagQuerySortOrder.cs
@@ -1,8 +1,22 @@
 namespace Enclave.Sdk.Api.Data.Tags;
 
+/// <summary>
+/// The sort order used for a Tag Query.
+/// </summary>
 public enum TagQuerySortOrder
 {
+    /// <summary>
+    /// Sort Alphabetically.
+    /// </summary>
     Alphabetical,
+
+    /// <summary>
+    /// Sort by recently used Tags.
+    /// </summary>
     RecentlyUsed,
+
+    /// <summary>
+    /// Sort by number of Referenced Systems.
+    /// </summary>
     ReferencedSystems,
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Data/UnaprrovedSystems/Enum/SystemType.cs b/src/Enclave.Sdk/Data/UnaprrovedSystems/Enum/SystemType.cs
index 9aa78a2..a69868d 100644
--- a/src/Enclave.Sdk/Data/UnaprrovedSystems/Enum/SystemType.cs
+++ b/src/Enclave.Sdk/Data/UnaprrovedSystems/Enum/SystemType.cs
@@ -1,7 +1,19 @@
 namespace Enclave.Sdk.Api.Data.UnaprrovedSystems.Enum;
 
+/// <summary>
+/// Defines the types of Enrolment Keys.
+/// </summary>
 public enum SystemType
 {
+    /// <summary>
+    /// For workstations, laptops, servers, and other systems that are relatively long-lived or manually provisioned.
+    /// Systems remain in your Enclave Organisation if they stop running.
+    /// </summary>
     GeneralPurpose,
+
+    /// <summary>
+    /// For containers, kubernetes pods, and other systems that are temporary, short-lived or automatically provisioned.
+    /// Systems are automatically removed from your Enclave Organisation when they stop/disconnect.
+    /// </summary>
     Ephemeral,
 }
diff --git a/src/Enclave.Sdk/Exceptions/ProblemDetailsException.cs b/src/Enclave.Sdk/Exceptions/ProblemDetailsException.cs
index af74bfc..676c931 100644
--- a/src/Enclave.Sdk/Exceptions/ProblemDetailsException.cs
+++ b/src/Enclave.Sdk/Exceptions/ProblemDetailsException.cs
@@ -1,15 +1,29 @@
 namespace Enclave.Sdk.Api.Exceptions;
 
-internal class ProblemDetailsException : Exception
+/// <summary>
+/// An Exception to display the details of an Http Problem Details.
+/// </summary>
+public class ProblemDetailsException : Exception
 {
+    /// <summary>
+    /// The Problem Details.
+    /// </summary>
     public ProblemDetails ProblemDetails { get; }
 
+    /// <summary>
+    /// The HttpResponse message.
+    /// </summary>
     public HttpResponseMessage Response { get; }
 
+    /// <summary>
+    /// Constructor for setting up the problem details exception.
+    /// </summary>
+    /// <param name="problemDetails">The problem details from the HTTP response.</param>
+    /// <param name="response">The HTTP Response message.</param>
     public ProblemDetailsException(ProblemDetails problemDetails, HttpResponseMessage response)
-        : base(problemDetails.Title)
+        : base(problemDetails?.Title)
     {
-        ProblemDetails = problemDetails;
+        ProblemDetails = problemDetails!;
         Response = response;
     }
 }
\ No newline at end of file
diff --git a/src/Enclave.Sdk/Handlers/ProblemDetailsHttpMessageHandler.cs b/src/Enclave.Sdk/Handlers/ProblemDetailsHttpMessageHandler.cs
index 5bbedfb..b063236 100644
--- a/src/Enclave.Sdk/Handlers/ProblemDetailsHttpMessageHandler.cs
+++ b/src/Enclave.Sdk/Handlers/ProblemDetailsHttpMessageHandler.cs
@@ -7,7 +7,9 @@ internal sealed class ProblemDetailsHttpMessageHandler : DelegatingHandler
 {
     public ProblemDetailsHttpMessageHandler()
 #pragma warning disable CA2000 // Dispose objects before losing scope
-        : base(new HttpClientHandler()) { }
+        : base(new HttpClientHandler())
+    {
+    }
 #pragma warning restore CA2000 // Dispose objects before losing scope
 
     protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken ct)