diff --git a/app/agent/tools/bigquery.py b/app/agent/tools/bigquery.py
index 013580f..c170ef8 100644
--- a/app/agent/tools/bigquery.py
+++ b/app/agent/tools/bigquery.py
@@ -143,10 +143,18 @@ def decode_table_values(
             f"Invalid table reference: '{table_gcp_id}'. Expected format: project.dataset.table"
         )
 
+    if table_name == "dicionario":
+        raise ValueError(
+            f"'{table_gcp_id}' is the dataset's dictionary table. "
+            "Pass the data table that holds the coded column instead."
+        )
+
     dict_table_id = f"`{project_name}.{dataset_name}.dicionario`"
 
+    # Some dictionaries store column names with stray whitespace
+    # (e.g. "col "), so compare and return them trimmed.
     search_query = f"""
-        SELECT nome_coluna, chave, valor
+        SELECT TRIM(nome_coluna) AS nome_coluna, chave, valor
         FROM {dict_table_id}
         WHERE id_tabela = @table_name
     """
@@ -156,9 +164,9 @@ def decode_table_values(
     ]
 
     if column_name is not None:
-        search_query += "AND nome_coluna = @column_name\n"
+        search_query += "AND TRIM(nome_coluna) = @column_name\n"
         query_params.append(
-            bq.ScalarQueryParameter("column_name", "STRING", column_name),
+            bq.ScalarQueryParameter("column_name", "STRING", column_name.strip()),
         )
 
     search_query += "ORDER BY nome_coluna, chave"
@@ -179,4 +187,12 @@ def decode_table_values(
     except NotFound as e:
         raise ValueError("Dictionary table not found for this dataset.") from e
 
+    if not results:
+        target = (
+            f"column '{column_name.strip()}' of " if column_name is not None else ""
+        )
+        raise ValueError(
+            f"No dictionary entries found for {target}table '{table_name}'."
+        )
+
     return json.dumps(results, ensure_ascii=False, indent=2, default=str)
diff --git a/tests/app/agent/tools/test_bigquery.py b/tests/app/agent/tools/test_bigquery.py
index 3f77e10..29c9117 100644
--- a/tests/app/agent/tools/test_bigquery.py
+++ b/tests/app/agent/tools/test_bigquery.py
@@ -461,13 +461,59 @@ def test_decode_specific_column(
 
         call_args = mock_bigquery_client.query.call_args[0][0]
         assert "id_tabela = @table_name" in call_args
-        assert "nome_coluna = @column_name" in call_args
+        assert "TRIM(nome_coluna) = @column_name" in call_args
 
         job_config = mock_bigquery_client.query.call_args[1]["job_config"]
         param_names = {p.name for p in job_config.query_parameters}
         assert "table_name" in param_names
         assert "column_name" in param_names
 
+    @pytest.mark.parametrize(
+        "column_name",
+        [
+            pytest.param("col1", id="stored-name-has-whitespace"),
+            pytest.param("col1 ", id="passed-name-has-whitespace"),
+        ],
+    )
+    def test_decode_specific_column_strips_whitespace(
+        self, mocker: MockerFixture, mock_context: AgentContext, column_name: str
+    ):
+        """Test that column names are matched and selected trimmed of stray whitespace.
+
+        Some dictionaries store names with stray whitespace (e.g. "col1 "), which the
+        model passes without it, so the query trims the stored names on both sides. The
+        mock stands in for BigQuery, so it returns the row already trimmed by that query.
+        """
+        mock_query_job = MagicMock()
+        mock_query_job.result.return_value = [
+            {"nome_coluna": "col1", "chave": "1", "valor": "Value 1"},
+        ]
+
+        mock_bigquery_client = MagicMock(spec=bq.Client)
+        mock_bigquery_client.query.return_value = mock_query_job
+
+        mocker.patch(
+            "app.agent.tools.bigquery._bq_client", return_value=mock_bigquery_client
+        )
+
+        message = _invoke_tool(
+            decode_table_values,
+            {"table_gcp_id": "project.dataset.table", "column_name": column_name},
+            context=mock_context,
+        )
+
+        output = json.loads(message.content)
+
+        assert output == [{"nome_coluna": "col1", "chave": "1", "valor": "Value 1"}]
+
+        call_args = mock_bigquery_client.query.call_args[0][0]
+        assert "SELECT TRIM(nome_coluna) AS nome_coluna" in call_args
+        assert "TRIM(nome_coluna) = @column_name" in call_args
+
+        job_config = mock_bigquery_client.query.call_args[1]["job_config"]
+        params = {p.name: p.value for p in job_config.query_parameters}
+        assert params["column_name"] == "col1"
+
     def test_dictionary_not_found(
         self, mocker: MockerFixture, mock_context: AgentContext
     ):
@@ -495,6 +541,84 @@ def test_dictionary_not_found(
         assert output["status"] == "error"
         assert output["message"] == "Dictionary table not found for this dataset."
 
+    def test_dictionary_table_passed_as_target(
+        self, mocker: MockerFixture, mock_context: AgentContext
+    ):
+        """Test error when the dictionary table itself is passed instead of a data table."""
+        mock_bigquery_client = MagicMock(spec=bq.Client)
+
+        mocker.patch(
+            "app.agent.tools.bigquery._bq_client", return_value=mock_bigquery_client
+        )
+
+        message = _invoke_tool(
+            decode_table_values,
+            {"table_gcp_id": "project.dataset.dicionario", "column_name": "col1"},
+            context=mock_context,
+        )
+
+        output = json.loads(message.content)
+
+        assert output["status"] == "error"
+        assert output["message"] == (
+            "'project.dataset.dicionario' is the dataset's dictionary table. "
+            "Pass the data table that holds the coded column instead."
+        )
+        mock_bigquery_client.query.assert_not_called()
+
+    def test_no_entries_for_column(
+        self, mocker: MockerFixture, mock_context: AgentContext
+    ):
+        """Test error when the dictionary has no entries for the requested column."""
+        mock_query_job = MagicMock()
+        mock_query_job.result.return_value = []
+
+        mock_bigquery_client = MagicMock(spec=bq.Client)
+        mock_bigquery_client.query.return_value = mock_query_job
+
+        mocker.patch(
+            "app.agent.tools.bigquery._bq_client", return_value=mock_bigquery_client
+        )
+
+        message = _invoke_tool(
+            decode_table_values,
+            {"table_gcp_id": "project.dataset.table", "column_name": "col1"},
+            context=mock_context,
+        )
+
+        output = json.loads(message.content)
+
+        assert output["status"] == "error"
+        assert (
+            output["message"]
+            == "No dictionary entries found for column 'col1' of table 'table'."
+        )
+
+    def test_no_entries_for_table(
+        self, mocker: MockerFixture, mock_context: AgentContext
+    ):
+        """Test error when the dictionary has no entries for the table."""
+        mock_query_job = MagicMock()
+        mock_query_job.result.return_value = []
+
+        mock_bigquery_client = MagicMock(spec=bq.Client)
+        mock_bigquery_client.query.return_value = mock_query_job
+
+        mocker.patch(
+            "app.agent.tools.bigquery._bq_client", return_value=mock_bigquery_client
+        )
+
+        message = _invoke_tool(
+            decode_table_values,
+            {"table_gcp_id": "project.dataset.table"},
+            context=mock_context,
+        )
+
+        output = json.loads(message.content)
+
+        assert output["status"] == "error"
+        assert output["message"] == "No dictionary entries found for table 'table'."
+
     def test_invalid_table_reference(self, mock_context: AgentContext):
         """Test error when table reference format is invalid."""
         message = _invoke_tool(