diff --git a/hermes_cli/config.py b/hermes_cli/config.py
index a818ed4203..5ddf37d082 100644
--- a/hermes_cli/config.py
+++ b/hermes_cli/config.py
@@ -538,6 +538,8 @@ DEFAULT_CONFIG = {
         "api_key": "",     # API key for delegation.base_url (falls back to OPENAI_API_KEY)
         "max_iterations": 50,  # per-subagent iteration cap (each subagent gets its own budget,
                                # independent of the parent's max_iterations)
+        "reasoning_effort": "",  # reasoning effort for subagents: "xhigh", "high", "medium",
+                                 # "low", "minimal", "none" (empty = inherit parent's level)
     },
 
     # Ephemeral prefill messages file — JSON list of {role, content} dicts
diff --git a/tests/tools/test_delegate.py b/tests/tools/test_delegate.py
index 5c64ff2868..3299b927e5 100644
--- a/tests/tools/test_delegate.py
+++ b/tests/tools/test_delegate.py
@@ -1210,5 +1210,73 @@ class TestDelegateHeartbeat(unittest.TestCase):
             f"Heartbeat should include last_activity_desc: {touch_calls}")
 
 
+class TestDelegationReasoningEffort(unittest.TestCase):
+    """Tests for delegation.reasoning_effort config override."""
+
+    @patch("tools.delegate_tool._load_config")
+    @patch("run_agent.AIAgent")
+    def test_inherits_parent_reasoning_when_no_override(self, MockAgent, mock_cfg):
+        """With no delegation.reasoning_effort, child inherits parent's config."""
+        mock_cfg.return_value = {"max_iterations": 50, "reasoning_effort": ""}
+        MockAgent.return_value = MagicMock()
+        parent = _make_mock_parent()
+        parent.reasoning_config = {"enabled": True, "effort": "xhigh"}
+
+        _build_child_agent(
+            task_index=0, goal="test", context=None, toolsets=None,
+            model=None, max_iterations=50, parent_agent=parent,
+        )
+        call_kwargs = MockAgent.call_args[1]
+        self.assertEqual(call_kwargs["reasoning_config"], {"enabled": True, "effort": "xhigh"})
+
+    @patch("tools.delegate_tool._load_config")
+    @patch("run_agent.AIAgent")
+    def test_override_reasoning_effort_from_config(self, MockAgent, mock_cfg):
+        """delegation.reasoning_effort overrides the parent's level."""
+        mock_cfg.return_value = {"max_iterations": 50, "reasoning_effort": "low"}
+        MockAgent.return_value = MagicMock()
+        parent = _make_mock_parent()
+        parent.reasoning_config = {"enabled": True, "effort": "xhigh"}
+
+        _build_child_agent(
+            task_index=0, goal="test", context=None, toolsets=None,
+            model=None, max_iterations=50, parent_agent=parent,
+        )
+        call_kwargs = MockAgent.call_args[1]
+        self.assertEqual(call_kwargs["reasoning_config"], {"enabled": True, "effort": "low"})
+
+    @patch("tools.delegate_tool._load_config")
+    @patch("run_agent.AIAgent")
+    def test_override_reasoning_effort_none_disables(self, MockAgent, mock_cfg):
+        """delegation.reasoning_effort: 'none' disables thinking for subagents."""
+        mock_cfg.return_value = {"max_iterations": 50, "reasoning_effort": "none"}
+        MockAgent.return_value = MagicMock()
+        parent = _make_mock_parent()
+        parent.reasoning_config = {"enabled": True, "effort": "high"}
+
+        _build_child_agent(
+            task_index=0, goal="test", context=None, toolsets=None,
+            model=None, max_iterations=50, parent_agent=parent,
+        )
+        call_kwargs = MockAgent.call_args[1]
+        self.assertEqual(call_kwargs["reasoning_config"], {"enabled": False})
+
+    @patch("tools.delegate_tool._load_config")
+    @patch("run_agent.AIAgent")
+    def test_invalid_reasoning_effort_falls_back_to_parent(self, MockAgent, mock_cfg):
+        """Invalid delegation.reasoning_effort falls back to parent's config."""
+        mock_cfg.return_value = {"max_iterations": 50, "reasoning_effort": "banana"}
+        MockAgent.return_value = MagicMock()
+        parent = _make_mock_parent()
+        parent.reasoning_config = {"enabled": True, "effort": "medium"}
+
+        _build_child_agent(
+            task_index=0, goal="test", context=None, toolsets=None,
+            model=None, max_iterations=50, parent_agent=parent,
+        )
+        call_kwargs = MockAgent.call_args[1]
+        self.assertEqual(call_kwargs["reasoning_config"], {"enabled": True, "effort": "medium"})
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/tools/delegate_tool.py b/tools/delegate_tool.py
index 7ec17264b7..f00701cd94 100644
--- a/tools/delegate_tool.py
+++ b/tools/delegate_tool.py
@@ -312,6 +312,25 @@ def _build_child_agent(
     effective_acp_command = override_acp_command or getattr(parent_agent, "acp_command", None)
     effective_acp_args = list(override_acp_args if override_acp_args is not None else (getattr(parent_agent, "acp_args", []) or []))
 
+    # Resolve reasoning config: delegation override > parent inherit
+    parent_reasoning = getattr(parent_agent, "reasoning_config", None)
+    child_reasoning = parent_reasoning
+    try:
+        delegation_cfg = _load_config()
+        delegation_effort = str(delegation_cfg.get("reasoning_effort") or "").strip()
+        if delegation_effort:
+            from hermes_constants import parse_reasoning_effort
+            parsed = parse_reasoning_effort(delegation_effort)
+            if parsed is not None:
+                child_reasoning = parsed
+            else:
+                logger.warning(
+                    "Unknown delegation.reasoning_effort '%s', inheriting parent level",
+                    delegation_effort,
+                )
+    except Exception as exc:
+        logger.debug("Could not load delegation reasoning_effort: %s", exc)
+
     child = AIAgent(
         base_url=effective_base_url,
         api_key=effective_api_key,
@@ -322,7 +341,7 @@ def _build_child_agent(
         acp_args=effective_acp_args,
         max_iterations=max_iterations,
         max_tokens=getattr(parent_agent, "max_tokens", None),
-        reasoning_config=getattr(parent_agent, "reasoning_config", None),
+        reasoning_config=child_reasoning,
         prefill_messages=getattr(parent_agent, "prefill_messages", None),
         enabled_toolsets=child_toolsets,
         quiet_mode=True,