diff --git a/docs/api.rst b/docs/api.rst
index ee42dd66..89727721 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -1,6 +1,14 @@
 API at a glance
 ===============
 
+Base containers
+---------------
+
+.. autosummary::
+  :toctree: _autosummary
+
+    jaxopt.OptStep
+
 Optimization
 ------------
 
@@ -180,4 +188,3 @@ Tree utilities
     jaxopt.tree_util.tree_sum
     jaxopt.tree_util.tree_l2_norm
     jaxopt.tree_util.tree_zeros_like
-
diff --git a/jaxopt/_src/base.py b/jaxopt/_src/base.py
index b6fc421d..55edda6d 100644
--- a/jaxopt/_src/base.py
+++ b/jaxopt/_src/base.py
@@ -46,6 +46,12 @@
 NUM_EVAL_DTYPE = 'int32'
 
 class OptStep(NamedTuple):
+  """Container returned by solvers.
+
+  Attributes:
+    params: solution parameters returned by the solver.
+    state: solver-specific state associated with ``params``.
+  """
   params: Any
   state: Any