diff --git a/run_agent.py b/run_agent.py
index 17b8b01db1..c8388bd0ae 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -5064,6 +5064,23 @@ class AIAgent:
             return tc.get("call_id", "") or tc.get("id", "") or ""
         return getattr(tc, "call_id", "") or getattr(tc, "id", "") or ""
 
+    @staticmethod
+    def _get_tool_call_name_static(tc) -> str:
+        """Extract function name from a tool_call entry (dict or object).
+
+        Gemini's OpenAI-compatibility endpoint requires every `role: tool`
+        message to carry the matching function name. OpenAI/Anthropic/ollama
+        tolerate its absence, so the field is best-effort: callers fall back
+        to "" and the message still works elsewhere.
+        """
+        if isinstance(tc, dict):
+            fn = tc.get("function")
+            if isinstance(fn, dict):
+                return fn.get("name", "") or ""
+            return ""
+        fn = getattr(tc, "function", None)
+        return getattr(fn, "name", "") or ""
+
     _VALID_API_ROLES = frozenset({"system", "user", "assistant", "tool", "function", "developer"})
 
     @staticmethod
@@ -5126,6 +5143,7 @@ class AIAgent:
                         if cid in missing_results:
                             patched.append({
                                 "role": "tool",
+                                "name": AIAgent._get_tool_call_name_static(tc),
                                 "content": "[Result unavailable — see context summary above]",
                                 "tool_call_id": cid,
                             })
@@ -9030,6 +9048,7 @@ class AIAgent:
                             insert_at,
                             {
                                 "role": "tool",
+                                "name": function_name if function_name != "?" else "",
                                 "tool_call_id": tool_call_id,
                                 "content": marker,
                             },
@@ -9434,6 +9453,7 @@ class AIAgent:
             for tc in tool_calls:
                 messages.append({
                     "role": "tool",
+                    "name": tc.function.name,
                     "content": f"[Tool execution cancelled — {tc.function.name} was skipped due to user interrupt]",
                     "tool_call_id": tc.id,
                 })
@@ -9775,6 +9795,7 @@ class AIAgent:
 
             tool_msg = {
                 "role": "tool",
+                "name": name,
                 "content": function_result,
                 "tool_call_id": tc.id,
             }
@@ -9812,6 +9833,7 @@ class AIAgent:
                     skipped_name = skipped_tc.function.name
                     skip_msg = {
                         "role": "tool",
+                        "name": skipped_name,
                         "content": f"[Tool execution cancelled — {skipped_name} was skipped due to user interrupt]",
                         "tool_call_id": skipped_tc.id,
                     }
@@ -10162,6 +10184,7 @@ class AIAgent:
 
             tool_msg = {
                 "role": "tool",
+                "name": function_name,
                 "content": function_result,
                 "tool_call_id": tool_call.id
             }
@@ -10188,6 +10211,7 @@ class AIAgent:
                     skipped_name = skipped_tc.function.name
                     skip_msg = {
                         "role": "tool",
+                        "name": skipped_name,
                         "content": f"[Tool execution skipped — {skipped_name} was not started. User sent a new message]",
                         "tool_call_id": skipped_tc.id
                     }
@@ -13110,6 +13134,7 @@ class AIAgent:
                                 content = "Skipped: another tool call in this turn used an invalid name. Please retry this tool call."
                             messages.append({
                                 "role": "tool",
+                                "name": tc.function.name,
                                 "tool_call_id": tc.id,
                                 "content": content,
                             })
@@ -13201,6 +13226,7 @@ class AIAgent:
                                     tool_result = "Skipped: other tool call in this response had invalid JSON."
                                 messages.append({
                                     "role": "tool",
+                                    "name": tc.function.name,
                                     "tool_call_id": tc.id,
                                     "content": tool_result,
                                 })
@@ -13717,6 +13743,7 @@ class AIAgent:
                             if tc["id"] not in answered_ids:
                                 err_msg = {
                                     "role": "tool",
+                                    "name": AIAgent._get_tool_call_name_static(tc),
                                     "tool_call_id": tc["id"],
                                     "content": f"Error executing tool: {error_msg}",
                                 }
diff --git a/tests/run_agent/test_agent_guardrails.py b/tests/run_agent/test_agent_guardrails.py
index 032057d59f..b222b3320e 100644
--- a/tests/run_agent/test_agent_guardrails.py
+++ b/tests/run_agent/test_agent_guardrails.py
@@ -263,3 +263,34 @@ class TestGetToolCallIdStatic:
     def test_object_without_id_attr(self):
         tc = types.SimpleNamespace()
         assert AIAgent._get_tool_call_id_static(tc) == ""
+
+
+# ---------------------------------------------------------------------------
+# _get_tool_call_name_static
+# ---------------------------------------------------------------------------
+
+class TestGetToolCallNameStatic:
+
+    def test_dict_with_valid_name(self):
+        assert AIAgent._get_tool_call_name_static(
+            {"id": "call_1", "function": {"name": "terminal", "arguments": "{}"}}
+        ) == "terminal"
+
+    def test_dict_with_missing_function(self):
+        assert AIAgent._get_tool_call_name_static({"id": "call_1"}) == ""
+
+    def test_dict_with_none_function(self):
+        assert AIAgent._get_tool_call_name_static({"id": "call_1", "function": None}) == ""
+
+    def test_dict_with_none_name(self):
+        assert AIAgent._get_tool_call_name_static(
+            {"function": {"name": None, "arguments": "{}"}}
+        ) == ""
+
+    def test_object_with_valid_name(self):
+        tc = make_tc("read_file")
+        assert AIAgent._get_tool_call_name_static(tc) == "read_file"
+
+    def test_object_without_function_attr(self):
+        tc = types.SimpleNamespace(id="call_1")
+        assert AIAgent._get_tool_call_name_static(tc) == ""
diff --git a/tests/run_agent/test_tool_call_args_sanitizer.py b/tests/run_agent/test_tool_call_args_sanitizer.py
index 79f4d82c5a..57ba9839fa 100644
--- a/tests/run_agent/test_tool_call_args_sanitizer.py
+++ b/tests/run_agent/test_tool_call_args_sanitizer.py
@@ -96,6 +96,7 @@ def test_marker_message_inserted_when_missing():
     assert repaired == 1
     assert messages[1] == {
         "role": "tool",
+        "name": "read_file",
         "tool_call_id": "call_1",
         "content": marker,
     }