diff --git a/ruma-client-api/src/r0/config/get_global_account_data.rs b/ruma-client-api/src/r0/config/get_global_account_data.rs
index 73285420..a97dbb59 100644
--- a/ruma-client-api/src/r0/config/get_global_account_data.rs
+++ b/ruma-client-api/src/r0/config/get_global_account_data.rs
@@ -15,16 +15,18 @@ ruma_api! {
         requires_authentication: true,
     }
 
+    #[non_exhaustive]
     request: {
         /// User ID of user for whom to retrieve data.
         #[ruma_api(path)]
-        pub user_id: UserId,
+        pub user_id: &'a UserId,
 
         /// Type of data to retrieve.
         #[ruma_api(path)]
-        pub event_type: String,
+        pub event_type: &'a str,
     }
 
+    #[non_exhaustive]
     response: {
         /// Account data content for the given type.
         #[ruma_api(body)]
@@ -33,3 +35,17 @@ ruma_api! {
 
     error: crate::Error
 }
+
+impl<'a> Request<'a> {
+    /// Creates a new `Request` with the given user ID and event type.
+    pub fn new(user_id: &'a UserId, event_type: &'a str) -> Self {
+        Self { user_id, event_type }
+    }
+}
+
+impl Response {
+    /// Creates a new `Response` with the given account data.
+    pub fn new(account_data: Raw<AnyBasicEvent>) -> Self {
+        Self { account_data }
+    }
+}
diff --git a/ruma-client-api/src/r0/config/get_room_account_data.rs b/ruma-client-api/src/r0/config/get_room_account_data.rs
index d3aa5dc2..82a780ed 100644
--- a/ruma-client-api/src/r0/config/get_room_account_data.rs
+++ b/ruma-client-api/src/r0/config/get_room_account_data.rs
@@ -15,20 +15,22 @@ ruma_api! {
         requires_authentication: true,
     }
 
+    #[non_exhaustive]
     request: {
         /// User ID of user for whom to retrieve data.
         #[ruma_api(path)]
-        pub user_id: UserId,
+        pub user_id: &'a UserId,
 
         /// Room ID for which to retrieve data.
         #[ruma_api(path)]
-        pub room_id: RoomId,
+        pub room_id: &'a RoomId,
 
         /// Type of data to retrieve.
         #[ruma_api(path)]
-        pub event_type: String,
+        pub event_type: &'a str,
     }
 
+    #[non_exhaustive]
     response: {
         /// Account data content for the given type.
         #[ruma_api(body)]
@@ -37,3 +39,17 @@ ruma_api! {
 
     error: crate::Error
 }
+
+impl<'a> Request<'a> {
+    /// Creates a new `Request` with the given user ID, room ID and event type.
+    pub fn new(user_id: &'a UserId, room_id: &'a RoomId, event_type: &'a str) -> Self {
+        Self { user_id, room_id, event_type }
+    }
+}
+
+impl Response {
+    /// Creates a new `Response` with the given account data.
+    pub fn new(account_data: Raw<AnyBasicEvent>) -> Self {
+        Self { account_data }
+    }
+}
diff --git a/ruma-client-api/src/r0/config/set_global_account_data.rs b/ruma-client-api/src/r0/config/set_global_account_data.rs
index eeabef26..c357c06a 100644
--- a/ruma-client-api/src/r0/config/set_global_account_data.rs
+++ b/ruma-client-api/src/r0/config/set_global_account_data.rs
@@ -14,6 +14,7 @@ ruma_api! {
         requires_authentication: true,
     }
 
+    #[non_exhaustive]
     request: {
         /// Arbitrary JSON to store as config data.
         ///
@@ -25,16 +26,32 @@ ruma_api! {
         ///
         /// Custom types should be namespaced to avoid clashes.
         #[ruma_api(path)]
-        pub event_type: String,
+        pub event_type: &'a str,
 
         /// The ID of the user to set account_data for.
         ///
         /// The access token must be authorized to make requests for this user ID.
         #[ruma_api(path)]
-        pub user_id: UserId,
+        pub user_id: &'a UserId,
     }
 
+    #[derive(Default)]
+    #[non_exhaustive]
     response: {}
 
     error: crate::Error
 }
+
+impl<'a> Request<'a> {
+    /// Creates a new `Request` with the given data, event type and user ID.
+    pub fn new(data: Box<RawJsonValue>, event_type: &'a str, user_id: &'a UserId) -> Self {
+        Self { data, event_type, user_id }
+    }
+}
+
+impl Response {
+    /// Creates an empty `Response`.
+    pub fn new() -> Self {
+        Self
+    }
+}
diff --git a/ruma-client-api/src/r0/config/set_room_account_data.rs b/ruma-client-api/src/r0/config/set_room_account_data.rs
index 63029553..c1a82f10 100644
--- a/ruma-client-api/src/r0/config/set_room_account_data.rs
+++ b/ruma-client-api/src/r0/config/set_room_account_data.rs
@@ -14,10 +14,11 @@ ruma_api! {
         requires_authentication: true,
     }
 
+    #[non_exhaustive]
     request: {
         /// Arbitrary JSON to store as config data.
         ///
-        /// To create a `Box<RawJsonValue>`, use `serde_json::value::to_raw_value`.
+        /// To create a `RawJsonValue`, use `serde_json::value::to_raw_value`.
         #[ruma_api(body)]
         pub data: Box<RawJsonValue>,
 
@@ -25,20 +26,41 @@ ruma_api! {
         ///
         /// Custom types should be namespaced to avoid clashes.
         #[ruma_api(path)]
-        pub event_type: String,
+        pub event_type: &'a str,
 
         /// The ID of the room to set account_data on.
         #[ruma_api(path)]
-        pub room_id: RoomId,
+        pub room_id: &'a RoomId,
 
         /// The ID of the user to set account_data for.
         ///
         /// The access token must be authorized to make requests for this user ID.
         #[ruma_api(path)]
-        pub user_id: UserId,
+        pub user_id: &'a UserId,
     }
 
+    #[derive(Default)]
+    #[non_exhaustive]
     response: {}
 
     error: crate::Error
 }
+
+impl<'a> Request<'a> {
+    /// Creates a new `Request` with the given data, event type, room ID and user ID.
+    pub fn new(
+        data: Box<RawJsonValue>,
+        event_type: &'a str,
+        room_id: &'a RoomId,
+        user_id: &'a UserId,
+    ) -> Self {
+        Self { data, event_type, room_id, user_id }
+    }
+}
+
+impl Response {
+    /// Creates an empty `Response`.
+    pub fn new() -> Self {
+        Self
+    }
+}
diff --git a/ruma-client-api/src/r0/contact/get_contacts.rs b/ruma-client-api/src/r0/contact/get_contacts.rs
index 792f69d7..cef4ef37 100644
--- a/ruma-client-api/src/r0/contact/get_contacts.rs
+++ b/ruma-client-api/src/r0/contact/get_contacts.rs
@@ -16,8 +16,11 @@ ruma_api! {
         requires_authentication: true,
     }
 
+    #[derive(Default)]
+    #[non_exhaustive]
     request: {}
 
+    #[non_exhaustive]
     response: {
         /// A list of third party identifiers the homeserver has associated with the user's
         /// account.
@@ -28,8 +31,26 @@ ruma_api! {
     error: crate::Error
 }
 
+impl Request {
+    /// Creates an empty `Request`.
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl Response {
+    /// Creates a new `Response` with the given third party identifiers.
+    pub fn new(threepids: Vec<ThirdPartyIdentifier>) -> Self {
+        Self { threepids }
+    }
+}
+
 /// An identifier external to Matrix.
+///
+/// To create an instance of this type, first create a `ThirdPartyIdentifierInit` and convert it to
+/// this type using `ThirdPartyIdentifier::Init` / `.into()`.
 #[derive(Clone, Debug, Deserialize, Serialize)]
+#[non_exhaustive]
 #[cfg_attr(test, derive(PartialEq))]
 pub struct ThirdPartyIdentifier {
     /// The third party identifier address.
@@ -47,6 +68,32 @@ pub struct ThirdPartyIdentifier {
     pub added_at: SystemTime,
 }
 
+/// Initial set of fields of `ThirdPartyIdentifier`.
+///
+/// This struct will not be updated even if additional fields are added to `ThirdPartyIdentifier`
+/// in a new (non-breaking) release of the Matrix specification.
+#[derive(Debug)]
+pub struct ThirdPartyIdentifierInit {
+    /// The third party identifier address.
+    pub address: String,
+
+    /// The medium of third party identifier.
+    pub medium: Medium,
+
+    /// The time when the identifier was validated by the identity server.
+    pub validated_at: SystemTime,
+
+    /// The time when the homeserver associated the third party identifier with the user.
+    pub added_at: SystemTime,
+}
+
+impl From<ThirdPartyIdentifierInit> for ThirdPartyIdentifier {
+    fn from(init: ThirdPartyIdentifierInit) -> Self {
+        let ThirdPartyIdentifierInit { address, medium, validated_at, added_at } = init;
+        ThirdPartyIdentifier { address, medium, validated_at, added_at }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::time::{Duration, UNIX_EPOCH};
diff --git a/ruma-client-api/src/r0/contact/request_contact_verification_token.rs b/ruma-client-api/src/r0/contact/request_contact_verification_token.rs
index 721106f2..470acb5b 100644
--- a/ruma-client-api/src/r0/contact/request_contact_verification_token.rs
+++ b/ruma-client-api/src/r0/contact/request_contact_verification_token.rs
@@ -13,35 +13,59 @@ ruma_api! {
         requires_authentication: false,
     }
 
+    #[non_exhaustive]
     request: {
         /// Client-generated secret string used to protect this session.
-        pub client_secret: String,
+        pub client_secret: &'a str,
 
         /// The email address.
-        pub email: String,
-
-        /// A URL for the identity server to redirect the user to after
-        /// validation is completed.
-        #[serde(skip_serializing_if = "Option::is_none")]
-        pub next_link: Option<String>,
+        pub email: &'a str,
 
         /// Used to distinguish protocol level retries from requests to re-send
         /// the email.
         pub send_attempt: UInt,
 
+        /// A URL for the identity server to redirect the user to after
+        /// validation is completed.
+        #[serde(skip_serializing_if = "Option::is_none")]
+        pub next_link: Option<&'a str>,
+
         /// The identity server to send the onward request to as a hostname with
         /// an appended colon and port number if the port is not the default.
         #[serde(skip_serializing_if = "Option::is_none")]
-        pub id_server: Option<String>,
+        pub id_server: Option<&'a str>,
 
         /// An access token previously registered with the identity server.
         ///
         /// Required if an `id_server` is supplied.
         #[serde(skip_serializing_if = "Option::is_none")]
-        pub id_access_token: Option<String>,
+        pub id_access_token: Option<&'a str>,
     }
 
+    #[derive(Default)]
+    #[non_exhaustive]
     response: {}
 
     error: crate::Error
 }
+
+impl<'a> Request<'a> {
+    /// Creates a new `Request` with the given client secret, email and send-attempt counter.
+    pub fn new(client_secret: &'a str, email: &'a str, send_attempt: UInt) -> Self {
+        Self {
+            client_secret,
+            email,
+            send_attempt,
+            next_link: None,
+            id_server: None,
+            id_access_token: None,
+        }
+    }
+}
+
+impl Response {
+    /// Creates an empty `Response`.
+    pub fn new() -> Self {
+        Self
+    }
+}