diff --git a/src/Guide/Api/Types.hs b/src/Guide/Api/Types.hs
index 091e934..333bcc6 100644
--- a/src/Guide/Api/Types.hs
+++ b/src/Guide/Api/Types.hs
@@ -92,14 +92,13 @@ data CategorySite route = CategorySite
       :> Description "Returns the ID of the created category.\n\n\
                      \If a category with the same title already exists, \
                      \returns its ID instead."
+      :> ErrorResponse 400 "'title' not provided"
       :> "category"
       :> QueryParam' '[Required, Strict] "title" Text
       :> Post '[JSON] (Uid Category)
 
   , _deleteCategory :: route :-
       Summary "Delete a category"
-      :> Description "Note: please ignore the 404 here, it's a bug \
-                     \in documentation. This endpoint does not return 404."
       :> "category"
       :> Capture "id" (Uid Category)
       :> Delete '[JSON] NoContent
@@ -111,6 +110,7 @@ data ItemSite route = ItemSite
   { _createItem :: route :-
       Summary "Create a new item in the given category"
       :> Description "Returns the ID of the created item."
+      :> ErrorResponse 400 "'name' not provided"
       :> "item"
       :> Capture "category" (Uid Category)
       :> QueryParam' '[Required, Strict] "name" Text
@@ -118,8 +118,6 @@ data ItemSite route = ItemSite
 
   , _deleteItem :: route :-
       Summary "Delete an item"
-      :> Description "Note: please ignore the 404 here, it's a bug \
-                     \in documentation. This endpoint does not return 404."
       :> "item"
       :> Capture "id" (Uid Item)
       :> Delete '[JSON] NoContent
@@ -130,8 +128,6 @@ data ItemSite route = ItemSite
 data TraitSite route = TraitSite
   { _deleteTrait :: route :-
       Summary "Delete a trait"
-      :> Description "Note: please ignore the 404 here, it's a bug \
-                     \in documentation. This endpoint does not return 404."
       :> "item"
       :> Capture "item" (Uid Item)
       :> "trait"
@@ -145,6 +141,7 @@ data SearchSite route = SearchSite
   { _search :: route :-
       Summary "Search categories and items"
       :> Description "Returns at most 100 search results"
+      :> ErrorResponse 400 "'query' not provided"
       :> "search"
       :> QueryParam' '[Required, Strict] "query" Text
       :> Get '[JSON] [CSearchResult]
diff --git a/stack.yaml b/stack.yaml
index f2769bc..bfc0ab5 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -22,17 +22,26 @@ extra-deps:
 - servant-swagger-ui-0.3.0.3.13.2
 - file-embed-lzma-0
 - servant-0.14.1
-- servant-swagger-1.1.5
 - servant-swagger-ui-core-0.3.1
 - swagger2-2.3
 - lzma-clib-5.2.2
-- git: https://github.com/neongreen/patches-vector
-  commit: 9bb704cf7f14cff9ef76a5d177e4e56ceee24705
+
 - git: https://github.com/aelve/stache-plus
   commit: c8097fb33df6ba738fc7b7c8d09aaebdb02a9782
+
 - git: https://github.com/aelve/safecopy-migrate
   commit: c401315122f04624e5e848d77f9eaa948e38c21b
+
+# Fork of 'servant-swagger' with some changes (see its README)
+- git: https://github.com/aelve/servant-swagger
+  commit: 09e124d03606ec54d50e3029ea86d096575d545c
+
+# Fork of 'hspec-webdriver' that builds
 - git: https://github.com/neongreen/webdriver-utils
   commit: db4a9027e62550c9d27110f36ae26c712acfbe95
   subdirs:
   - hspec-webdriver
+
+# Fork of 'patches-vector' that builds
+- git: https://github.com/neongreen/patches-vector
+  commit: 9bb704cf7f14cff9ef76a5d177e4e56ceee24705