diff --git a/meshmode/interop/firedrake/connection.py b/meshmode/interop/firedrake/connection.py
index 9c5c8eb80d43f402ea7d74a8ac14072c060c6302..b63dfc9a5716034cf9a4b50d469ca0ff52e00792 100644
--- a/meshmode/interop/firedrake/connection.py
+++ b/meshmode/interop/firedrake/connection.py
@@ -539,6 +539,10 @@ class FromBdyFiredrakeConnection(FiredrakeConnection):
     meshmode discretization corresponding to all cells with at
     least one vertex on the given boundary and allows
     transfer of functions to and from :mod:`firedrake`.
+
+    Use the same bdy_id as one would for a
+    :class:`firedrake.bcs.DirichletBC`.
+    ``"on_boundary"`` corresponds to the entire boundary.
     """
     def __init__(self, cl_ctx, fdrake_fspace, bdy_id):
         """
diff --git a/meshmode/interop/firedrake/mesh.py b/meshmode/interop/firedrake/mesh.py
index 5ce3a674e851da7a47b4b2322c22efa3984cadb3..569a3b9fa870edbddfd8ce41a73640ba763cdf8e 100644
--- a/meshmode/interop/firedrake/mesh.py
+++ b/meshmode/interop/firedrake/mesh.py
@@ -460,6 +460,9 @@ def import_firedrake_mesh(fdrake_mesh, cells_to_use=None,
         returned mesh. These "induced" boundaries are marked with
         :class:`BTAG_NO_BOUNDARY` (and :class:`BTAG_REALLY_ALL`)
         instead of :class:`BTAG_ALL`.
+
+        This argument is primarily intended for use by a
+        :class:`meshmode.interop.firedrake.FromBdyFiredrakeConnection`.
     :arg normals: **Only** used if *fdrake_mesh* is a 1-surface
         embedded in 2-space. In this case,
             - If *None* then