diff --git a/builtin-doc/coq-builtin.elpi b/builtin-doc/coq-builtin.elpi
index a6a858b95..4d62b1f8b 100644
--- a/builtin-doc/coq-builtin.elpi
+++ b/builtin-doc/coq-builtin.elpi
@@ -1619,6 +1619,11 @@ external pred coq.ltac.collect-goals i:term, o:list sealed-goal,
 % of type ltac1-tactic, see the tac argument constructor
 % and the ltac_tactic:(...) syntax to pass arguments to
 % an elpi tactic.
+% Caveat:
+%   if Tac is a tactic name, then the tactic must be defined using
+%   "Ltac name := body", it cannot be a builtin one. For example
+%   "Ltac myapply x := apply x." lets one call apply by running
+%   coq.ltac.call-ltac1 "myapply" G GL.
 % Supported attributes:
 % - @no-tc! (default false, do not infer typeclasses)
 external pred coq.ltac.call-ltac1 i:any, i:goal, o:list sealed-goal.
diff --git a/src/coq_elpi_builtins.ml b/src/coq_elpi_builtins.ml
index f62085953..a1d3dd73a 100644
--- a/src/coq_elpi_builtins.ml
+++ b/src/coq_elpi_builtins.ml
@@ -3709,6 +3709,11 @@ Tac can either be a string (the tactic name), or a value
 of type ltac1-tactic, see the tac argument constructor
 and the ltac_tactic:(...) syntax to pass arguments to
 an elpi tactic.
+Caveat:
+  if Tac is a tactic name, then the tactic must be defined using
+  "Ltac name := body", it cannot be a builtin one. For example
+  "Ltac myapply x := apply x." lets one call apply by running
+  coq.ltac.call-ltac1 "myapply" G GL.
 Supported attributes:
 - @no-tc! (default false, do not infer typeclasses)|})))),
     (fun tac (proof_context,goal,tac_args) _ ~depth _ _ -> abstract__grab_global_env_keep_sigma "coq.ltac.call-ltac1" (fun state ->