diff --git a/strix/agents/prompts/system_prompt.jinja b/strix/agents/prompts/system_prompt.jinja
index 5fc697d7..3efc07af 100644
--- a/strix/agents/prompts/system_prompt.jinja
+++ b/strix/agents/prompts/system_prompt.jinja
@@ -39,6 +39,8 @@ INTERACTIVE BEHAVIOR:
   - To end the whole engagement, call the lifecycle tool: finish_scan (root) or agent_finish (subagent).
   - A turn that ends with plain text and no tool call does NOT stop you: the system nudges you to continue and will re-run you. Do not rely on going silent to pause — it will not pause you.
 - Answering a user question: put the answer in respond_to_user's message. Do not write the answer as plain text and then fall silent — that does not reach a stopping point, it just triggers a continuation nudge.
+- If all you want to do is reply and stop, that whole turn is ONE respond_to_user call carrying the answer. Do not write the answer as text and then call respond_to_user as well: the user reads it twice.
+- If you do end a turn on plain text and the nudge arrives, your words already reached the user. Do not restate them: call respond_to_user with NO message to simply wait, or with only whatever you still need to add.
 - You may include brief explanatory text before a tool call, and you can narrate while you work — plain text is shown to the user as you go. Narrating is free; respond_to_user is specifically the act of WAITING for the user, so do not call it just to give a status update.
 - Respond naturally when the user asks questions or gives instructions.
 - While actively working on a task, every turn should carry exactly one tool call — use think to plan, the appropriate tool to act, and respond_to_user only when you genuinely need the user.
diff --git a/strix/core/execution.py b/strix/core/execution.py
index 91ceb8af..bd99e7c3 100644
--- a/strix/core/execution.py
+++ b/strix/core/execution.py
@@ -830,7 +830,7 @@ async def _append_tool_required_message(
             "execution and never hands control to the user: it is shown to the user, and the "
             "run continues. Continue immediately and call exactly one tool. "
             "If you have something to tell the user and nothing to do until they reply, "
-            "call respond_to_user. "
+            "call respond_to_user — with no message if you have already said it. "
             "If you are blocked waiting for another agent, call wait_for_agents. "
             f"If the whole engagement is complete, call {finish_tool}. "
             "Otherwise use the appropriate execution or planning tool. "
diff --git a/strix/tools/respond/tool.py b/strix/tools/respond/tool.py
index 796050c3..12538f0c 100644
--- a/strix/tools/respond/tool.py
+++ b/strix/tools/respond/tool.py
@@ -15,7 +15,7 @@ def _ctx(ctx: RunContextWrapper) -> dict[str, Any]:
 
 
 @function_tool
-async def respond_to_user(ctx: RunContextWrapper, message: str) -> str:
+async def respond_to_user(ctx: RunContextWrapper, message: str = "") -> str:
     """Answer the user and hand control back to them.
 
     This is the ONLY way to yield to the user. Delivering the message and
@@ -45,6 +45,10 @@ async def respond_to_user(ctx: RunContextWrapper, message: str) -> str:
             have followed the tool calls that led here. Lead with the
             answer or the decision you need, and if you are blocked, say
             exactly what you need from them.
+
+            Omit it when you have just said your piece as plain text and
+            only need to wait: that text has already reached them, and
+            repeating it makes them read the same answer twice.
     """
     inner = _ctx(ctx)
     coordinator = coordinator_from_context(inner)
diff --git a/tests/test_execution.py b/tests/test_execution.py
index 6364f801..d389bde3 100644
--- a/tests/test_execution.py
+++ b/tests/test_execution.py
@@ -1228,3 +1228,40 @@ async def test_wait_kind_survives_a_snapshot_round_trip() -> None:
     assert restored.wait_kinds["root"] == "user"
     assert restored.idle_resume_counts["root"] == 1
     assert await execution._plain_waiting_timeout(restored, "root") is None
+
+
+@pytest.mark.asyncio
+async def test_interactive_nudge_offers_waiting_without_repeating() -> None:
+    """The nudge is the instruction an agent reads when it is stranded here.
+
+    It is where the option to wait on what was already said has to be, not only
+    in the system prompt: an agent that ended a turn on plain text reasons off
+    this text, and without the clause it restates its answer to reach a tool
+    call, so the user reads it twice.
+
+    The clause holds whatever the turn did, because the agent is the one who
+    knows whether it spoke — this fires for a turn that produced no text at all.
+    """
+    items = await execution._append_tool_required_message(
+        session=None,
+        context={"parent_id": None},
+        attempt=1,
+        limit=3,
+        interactive=True,
+    )
+
+    assert "with no message if you have already said it" in items[0]["content"]
+
+
+@pytest.mark.asyncio
+async def test_autonomous_nudge_does_not_offer_the_user() -> None:
+    """There is nobody attached to an autonomous run to wait for."""
+    items = await execution._append_tool_required_message(
+        session=None,
+        context={"parent_id": None},
+        attempt=1,
+        limit=3,
+        interactive=False,
+    )
+
+    assert "respond_to_user" not in items[0]["content"]
diff --git a/tests/test_respond_to_user.py b/tests/test_respond_to_user.py
index 254bd357..fc59c267 100644
--- a/tests/test_respond_to_user.py
+++ b/tests/test_respond_to_user.py
@@ -64,3 +64,31 @@ async def test_a_message_that_already_arrived_is_taken_instead_of_parking() -> N
     assert result["wait_outcome"] == "message_arrived"
     assert result["pending_messages"] == 1
     assert coordinator.statuses["root"] == "running"
+
+
+async def _call_without_message(context: dict[str, Any]) -> dict[str, Any]:
+    ctx = ToolContext(
+        context=context,
+        tool_name="respond_to_user",
+        tool_call_id="call-1",
+        tool_arguments="{}",
+    )
+    raw = await respond_to_user.on_invoke_tool(ctx, "{}")
+    return json.loads(raw)  # type: ignore[no-any-return]
+
+
+@pytest.mark.asyncio
+async def test_parks_without_a_message() -> None:
+    """An agent that has already said its piece as plain text can just wait.
+
+    The nudge is what leaves it here, and while a message was required the only
+    way to stop was to send the same answer a second time.
+    """
+    context = await _context(interactive=True)
+
+    result = await _call_without_message(context)
+
+    assert result["success"] is True
+    assert result["wait_outcome"] == "waiting"
+    assert result["message"] == ""
+    assert context["coordinator"].statuses["root"] == "waiting"