diff --git a/docs/operators/reduce.md b/docs/operators/reduce.md
index 78eb064f..f8407d4a 100644
--- a/docs/operators/reduce.md
+++ b/docs/operators/reduce.md
@@ -43,7 +43,7 @@ This Reduce operation processes customer feedback grouped by department:
 ### Required Parameters
 
 - `type`: Must be set to "reduce".
-- `reduce_key`: The key (or list of keys) to use for grouping data.
+- `reduce_key`: The key (or list of keys) to use for grouping data. Use `_all` to group all data into one group.
 - `prompt`: The prompt template to use for the reduction operation.
 - `output`: Schema definition for the output from the LLM.
 
diff --git a/todos.md b/todos.md
index 15525b59..4f4e301d 100644
--- a/todos.md
+++ b/todos.md
@@ -73,7 +73,7 @@ TODO:
 - [x] Add gleaning plan to reduce
 - [ ] HITL for prompt selection (generally, a textual app)
 - [ ] Fix bug in recursively optimizing reduce in the map optimizer
-- [ ] Support reduce key of "all"
+- [x] Support reduce key of "all"
 - [ ] Write tests for optimizers
 - [ ] Refactor reduce and join optimizers
 - [ ] Support prompt prefix/custom instructions so users don't have to put them in every operation