diff --git a/openflexure_microscope/api/default_extensions/zip_builder.py b/openflexure_microscope/api/default_extensions/zip_builder.py
index 74444a07..50103a2f 100644
--- a/openflexure_microscope/api/default_extensions/zip_builder.py
+++ b/openflexure_microscope/api/default_extensions/zip_builder.py
@@ -149,15 +149,23 @@ class ZipBuilderAPIView(ActionView):
     args = fields.List(fields.String(), required=True)
 
     def post(self, args):
+        """Build a zip file of some captures
+        
+        Given a list of capture IDs as its argument, this action will
+        create a zip file that can be downloaded once the action has
+        completed.
+        """
         microscope = find_component("org.openflexure.microscope")
 
-        # Return a handle on the autofocus task
+        # Build a zip file from the supplied IDs
         return self.extension.manager.marshaled_build_zip_from_capture_ids(
             microscope, args
         )
 
 
 class ZipListAPIView(PropertyView):
+    """List all the zip files currently available for download.
+    """
     schema = ZipObjectSchema(many=True)
 
     def get(self):
@@ -165,9 +173,22 @@ class ZipListAPIView(PropertyView):
 
 
 class ZipGetterAPIView(View):
+    """Download or delete a particular capture collection ZIP file
     """
-    Download or delete a particular capture collection ZIP file
-    """
+    parameters = [
+        {
+            "name": "session_id",
+            "in": "path",
+            "description": "The unique ID of the zip builder session",
+            "required": True,
+            "schema": { "type": "string" },
+        }
+    ]
+    responses = {
+        404: {
+            "description": "The session ID could not be found",
+        }
+    }
 
     def get(self, session_id):
         """
@@ -176,7 +197,7 @@ class ZipGetterAPIView(View):
         if not session_id in self.extension.manager.session_zips:
             return abort(404)  # 404 Not Found
 
-        logging.info("Session ID: %s", session_id)
+        logging.info("Retrieving zip (session ID: %s)", session_id)
 
         return send_file(
             self.extension.manager.zip_fp_from_id(session_id).name,
@@ -184,6 +205,12 @@ class ZipGetterAPIView(View):
             as_attachment=True,
             attachment_filename=f"{session_id}.zip",
         )
+    get.responses = {
+        200: {
+            "content": {"application/zip": {}}, 
+            "description": "A zip archive containing the selected captures",
+        },
+    }
 
     def delete(self, session_id):
         """
@@ -198,3 +225,8 @@ class ZipGetterAPIView(View):
         del self.extension.manager.session_zips[session_id]
 
         return {"return": session_id}
+    delete.responses = {
+        200: {
+            "description": "The zip file was deleted",
+        },
+    }