diff --git a/agent/tools/google.py b/agent/tools/google.py
index a5fb4bdf29..d86c8302c5 100644
--- a/agent/tools/google.py
+++ b/agent/tools/google.py
@@ -498,13 +498,23 @@ class Google(ToolBase, ABC):
                 if self.check_if_canceled("Google processing"):
                     return
 
+                # serpapi reports an invalid key, exhausted quota or an empty result
+                # set through an "error" field and omits "organic_results"; surface that
+                # message instead of raising a cryptic KeyError on the missing key.
+                if "organic_results" not in search:
+                    raise RuntimeError(search.get("error", "SerpApi returned no organic_results."))
+
+                organic_results = search["organic_results"]
+                # a result may omit any of these; note the fallback of the "description"
+                # lookup is evaluated eagerly, so it has to be a .get() too or a result
+                # carrying a description but no snippet raises KeyError.
                 self._retrieve_chunks(
-                    search["organic_results"],
-                    get_title=lambda r: r["title"],
-                    get_url=lambda r: r["link"],
-                    get_content=lambda r: r.get("about_this_result", {}).get("source", {}).get("description", r["snippet"]),
+                    organic_results,
+                    get_title=lambda r: r.get("title", ""),
+                    get_url=lambda r: r.get("link", ""),
+                    get_content=lambda r: r.get("about_this_result", {}).get("source", {}).get("description", r.get("snippet", "")),
                 )
-                self.set_output("json", search["organic_results"])
+                self.set_output("json", organic_results)
                 return self.output("formalized_content")
             except Exception as e:
                 if self.check_if_canceled("Google processing"):
diff --git a/test/unit_test/agent/tools/test_google_unit.py b/test/unit_test/agent/tools/test_google_unit.py
new file mode 100644
index 0000000000..f544f1b975
--- /dev/null
+++ b/test/unit_test/agent/tools/test_google_unit.py
@@ -0,0 +1,98 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+import pytest
+
+# Google imports the `serpapi` SDK at module load; skip where absent.
+pytest.importorskip("serpapi")
+
+import agent.tools.google as g_module  # noqa: E402
+from agent.tools.google import Google, GoogleParam  # noqa: E402
+
+
+class _FakeSearch:
+    """Stands in for serpapi.GoogleSearch; get_dict() returns a canned response."""
+
+    def __init__(self, result):
+        self._result = result
+
+    def get_dict(self):
+        return self._result
+
+
+def _make_tool():
+    # Bypass the canvas-bound __init__ (mirrors test_googlescholar.py) and stub the
+    # canvas-touching helpers so we can exercise _invoke's response handling. Zero the
+    # error delay so the failing path doesn't sleep.
+    g = Google.__new__(Google)
+    param = GoogleParam()
+    param.api_key = "k"
+    param.max_retries = 0
+    param.delay_after_error = 0
+    g._param = param
+    g.check_if_canceled = lambda *a, **k: False
+
+    captured = {}
+    out = {}
+
+    def fake_retrieve(res_list, get_title=None, get_url=None, get_content=None, **_kw):
+        # The real _retrieve_chunks applies these getters to every result; replicate
+        # that so the tests actually exercise the lambdas, which is where the
+        # per-result KeyErrors came from.
+        items = list(res_list)
+        captured["chunks"] = items
+        captured["rendered"] = [{"title": get_title(r), "url": get_url(r), "content": get_content(r)} for r in items]
+        out["formalized_content"] = "FC"
+
+    g._retrieve_chunks = fake_retrieve
+    g.set_output = lambda k, v: out.__setitem__(k, v)
+    g.output = lambda k=None: out.get(k) if k else out
+    return g, captured, out
+
+
+def test_error_response_surfaces_serpapi_message(monkeypatch):
+    # Regression: on an invalid key / exhausted quota / no-match, serpapi returns
+    # {"error": ...} with no "organic_results". The tool used to raise
+    # KeyError('organic_results'), reported to the model as the opaque
+    # "Google error: 'organic_results'". It must surface serpapi's real message.
+    monkeypatch.setattr(g_module, "GoogleSearch", lambda params: _FakeSearch({"error": "Invalid API key."}))
+    g, _, out = _make_tool()
+    result = g._invoke(q="anything")
+    assert "Invalid API key." in result
+    assert "organic_results" not in result
+    assert out.get("_ERROR") == "Invalid API key."
+
+
+def test_valid_response_returns_results(monkeypatch):
+    results = [{"title": "t", "link": "u", "snippet": "s"}]
+    monkeypatch.setattr(g_module, "GoogleSearch", lambda params: _FakeSearch({"organic_results": results}))
+    g, captured, out = _make_tool()
+    g._invoke(q="anything")
+    assert captured["chunks"] == results
+    assert captured["rendered"] == [{"title": "t", "url": "u", "content": "s"}]
+    assert out["json"] == results
+
+
+def test_result_missing_optional_fields_does_not_raise(monkeypatch):
+    # Regression: get_content's fallback `r["snippet"]` was evaluated eagerly, so a
+    # result carrying a description but no snippet raised KeyError('snippet') -- the
+    # very failure mode this tool's error handling exists to prevent. title and link
+    # may be absent on a result too.
+    results = [{"about_this_result": {"source": {"description": "d"}}}]
+    monkeypatch.setattr(g_module, "GoogleSearch", lambda params: _FakeSearch({"organic_results": results}))
+    g, captured, _ = _make_tool()
+    g._invoke(q="anything")
+    assert captured["rendered"] == [{"title": "", "url": "", "content": "d"}]