diff --git a/openapi/components/paths/invite.yaml b/openapi/components/paths/invite.yaml
index afce0e57..140c486e 100644
--- a/openapi/components/paths/invite.yaml
+++ b/openapi/components/paths/invite.yaml
@@ -102,6 +102,12 @@ paths:
         - apiKeyCookie: []
           authCookie: []
       description: Sends an invite to a user. Returns the Notification of type `invite` that was sent.
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: ../requests/InviteRequest.yaml
+        description: Instance ID when inviting a user.
   '/invite/{notificationId}/response':
     parameters:
       - $ref: ../parameters.yaml#/notificationId
@@ -119,6 +125,12 @@ paths:
         - apiKeyCookie: []
           authCookie: []
       description: Sends a world invite to a user.
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: ../requests/InviteResponse.yaml
+        description: Instance ID when inviting a user.
   '/requestInvite/{userId}':
     parameters:
       - $ref: ../parameters.yaml#/userId
diff --git a/openapi/components/requests/InviteRequest.yaml b/openapi/components/requests/InviteRequest.yaml
new file mode 100644
index 00000000..5075d403
--- /dev/null
+++ b/openapi/components/requests/InviteRequest.yaml
@@ -0,0 +1,7 @@
+title: InviteRequest
+type: object
+properties:
+  instanceId:
+    $ref: ../schemas/InstanceID.yaml
+required:
+  - instanceId
\ No newline at end of file
diff --git a/openapi/components/requests/InviteResponse.yaml b/openapi/components/requests/InviteResponse.yaml
new file mode 100644
index 00000000..cc8247a8
--- /dev/null
+++ b/openapi/components/requests/InviteResponse.yaml
@@ -0,0 +1,9 @@
+type: object
+properties:
+  responseSlot:
+    type: integer
+    minimum: 0
+    maximum: 11
+required:
+  - responseSlot
+title: InviteResponse
diff --git a/openapi/components/schemas/Instance.yaml b/openapi/components/schemas/Instance.yaml
index c8a2367e..1867f291 100644
--- a/openapi/components/schemas/Instance.yaml
+++ b/openapi/components/schemas/Instance.yaml
@@ -19,8 +19,7 @@ properties:
     type: boolean
     default: false
   id:
-    type: string
-    minLength: 1
+    $ref: ./InstanceID.yaml
   instanceId:
     type: string
     minLength: 1
diff --git a/openapi/components/schemas/InstanceID.yaml b/openapi/components/schemas/InstanceID.yaml
new file mode 100644
index 00000000..904106e2
--- /dev/null
+++ b/openapi/components/schemas/InstanceID.yaml
@@ -0,0 +1,4 @@
+title: InstanceID
+type: string
+pattern: '(wrld|wld)_[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}:(\d+)(~region\(([\w]+)\))?(~([\w]+)\(usr_([\w-]+)\)((\~canRequestInvite)?)(~region\(([\w].+)\))?~nonce\((.+)\))?'
+example: wrld_ba913a96-fac4-4048-a062-9aa5db092812:123456
\ No newline at end of file
diff --git a/openapi/components/schemas/InviteMessage.yaml b/openapi/components/schemas/InviteMessage.yaml
index c7178b7e..09e9a6b5 100644
--- a/openapi/components/schemas/InviteMessage.yaml
+++ b/openapi/components/schemas/InviteMessage.yaml
@@ -7,6 +7,7 @@ properties:
   slot:
     type: integer
     minimum: 0
+    maximum: 11
   message:
     type: string
     minLength: 1