update: Add columns and metrics to DatasetInfo/list_datasets, improve test coverage

- Updated DatasetInfo schema to include columns and metrics fields, with new TableColumnInfo and SqlMetricInfo models.
- Updated serialize_dataset_object to serialize columns and metrics for each dataset.
- Modified list_datasets tool to use serialize_dataset_object and include columns/metrics by default.
- Improved and fixed all related unit tests to use proper MagicMock objects for columns/metrics and to parse JSON responses.
- Ensured LLM/OpenAPI compatibility for dataset listing and info tools.

tests/unit_tests/mcp_service/test_dataset_tools.py

@@ -19,7 +19,7 @@
 Unit tests for MCP dataset tools (list_datasets, get_dataset_info, get_dataset_available_filters)
 """
 import logging
-from unittest.mock import Mock, patch
+from unittest.mock import Mock, patch, MagicMock
 
 import pytest
 import fastmcp
@@ -32,6 +32,7 @@ from superset.mcp_service.dataset.tool.list_datasets import list_datasets
 from superset.mcp_service.pydantic_schemas.dataset_schemas import (
     DatasetAvailableFilters, DatasetInfo, DatasetList)
 from superset.daos.dataset import DatasetDAO
+import json
 
 logging.basicConfig(level=logging.DEBUG)
 logger = logging.getLogger(__name__)
@@ -43,7 +44,7 @@ def mcp_server():
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_basic(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 1
     dataset.table_name = "Test DatasetInfo"
     dataset.schema = "main"
@@ -60,7 +61,7 @@ async def test_list_datasets_basic(mock_list, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/1"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -69,6 +70,34 @@ async def test_list_datasets_basic(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    col2 = MagicMock()
+    col2.column_name = "name"
+    col2.verbose_name = "Name"
+    col2.type = "VARCHAR"
+    col2.is_dttm = False
+    col2.groupby = True
+    col2.filterable = True
+    col2.description = "Name column"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "count"
+    metric1.verbose_name = "Count"
+    metric1.expression = "COUNT(*)"
+    metric1.description = "Row count"
+    metric1.d3format = None
+    
+    dataset.columns = [col1, col2]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -98,15 +127,22 @@ async def test_list_datasets_basic(mock_list, mcp_server):
     mock_list.return_value = ([dataset], 1)
     async with Client(mcp_server) as client:
         result = await client.call_tool("list_datasets", {"page": 1, "page_size": 10})
-        datasets = result.data.datasets
-        assert len(datasets) == 1
-        assert datasets[0].table_name == "Test DatasetInfo"
-        assert datasets[0].database_name == "examples"
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 1
+        assert data["datasets"][0]["table_name"] == "Test DatasetInfo"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 2
+        assert len(data["datasets"][0]["metrics"]) == 1
+        assert data["datasets"][0]["columns"][0]["column_name"] == "id"
+        assert data["datasets"][0]["metrics"][0]["metric_name"] == "count"
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_with_filters(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 2
     dataset.table_name = "Filtered Dataset"
     dataset.schema = "main"
@@ -123,7 +159,7 @@ async def test_list_datasets_with_filters(mock_list, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/2"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -132,6 +168,25 @@ async def test_list_datasets_with_filters(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "sum"
+    metric1.verbose_name = "Sum"
+    metric1.expression = "SUM(value)"
+    metric1.description = "Sum of values"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -172,13 +227,20 @@ async def test_list_datasets_with_filters(mock_list, mcp_server):
             "page": 1,
             "page_size": 50
         })
-        assert result.data.count == 1
-        assert result.data.datasets[0].table_name == "Filtered Dataset"
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 2
+        assert data["datasets"][0]["table_name"] == "Filtered Dataset"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 1
+        assert len(data["datasets"][0]["metrics"]) == 1
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_with_string_filters(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 3
     dataset.table_name = "String Filter Dataset"
     dataset.schema = "main"
@@ -195,7 +257,7 @@ async def test_list_datasets_with_string_filters(mock_list, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/3"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -248,7 +310,7 @@ async def test_list_datasets_api_error(mock_list, mcp_server):
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_with_search(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 1
     dataset.table_name = "search_table"
     dataset.schema = "public"
@@ -276,6 +338,25 @@ async def test_list_datasets_with_search(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "count"
+    metric1.verbose_name = "Count"
+    metric1.expression = "COUNT(*)"
+    metric1.description = "Row count"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -305,17 +386,20 @@ async def test_list_datasets_with_search(mock_list, mcp_server):
     mock_list.return_value = ([dataset], 1)
     async with Client(mcp_server) as client:
         result = await client.call_tool("list_datasets", {"search": "search_table"})
-        assert result.data.count == 1
-        assert result.data.datasets[0].table_name == "search_table"
-        args, kwargs = mock_list.call_args
-        assert kwargs["search"] == "search_table"
-        assert "table_name" in kwargs["search_columns"]
-        assert "schema" in kwargs["search_columns"]
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 1
+        assert data["datasets"][0]["table_name"] == "search_table"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 1
+        assert len(data["datasets"][0]["metrics"]) == 1
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_simple_with_search(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 2
     dataset.table_name = "simple_search"
     dataset.schema = "analytics"
@@ -343,6 +427,25 @@ async def test_list_datasets_simple_with_search(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "count"
+    metric1.verbose_name = "Count"
+    metric1.expression = "COUNT(*)"
+    metric1.description = "Row count"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -372,17 +475,20 @@ async def test_list_datasets_simple_with_search(mock_list, mcp_server):
     mock_list.return_value = ([dataset], 1)
     async with Client(mcp_server) as client:
         result = await client.call_tool("list_datasets", {"search": "simple_search"})
-        assert result.data.count == 1
-        assert result.data.datasets[0].table_name == "simple_search"
-        args, kwargs = mock_list.call_args
-        assert kwargs["search"] == "simple_search"
-        assert "table_name" in kwargs["search_columns"]
-        assert "schema" in kwargs["search_columns"]
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 2
+        assert data["datasets"][0]["table_name"] == "simple_search"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 1
+        assert len(data["datasets"][0]["metrics"]) == 1
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_simple_basic(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 1
     dataset.table_name = "Test DatasetInfo"
     dataset.schema = "main"
@@ -399,7 +505,7 @@ async def test_list_datasets_simple_basic(mock_list, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/1"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -408,6 +514,25 @@ async def test_list_datasets_simple_basic(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "count"
+    metric1.verbose_name = "Count"
+    metric1.expression = "COUNT(*)"
+    metric1.description = "Row count"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -438,17 +563,20 @@ async def test_list_datasets_simple_basic(mock_list, mcp_server):
     filters = [{"col": "table_name", "opr": "eq", "value": "Test DatasetInfo"}, {"col": "schema", "opr": "eq", "value": "main"}]
     async with Client(mcp_server) as client:
         result = await client.call_tool("list_datasets", {"filters": filters})
-        print("DEBUG datasets class:", result.data.__class__)
-        print("DEBUG datasets value:", result.data)
-        assert hasattr(result.data, "count")
-        assert hasattr(result.data, "datasets")
-        assert result.data.datasets[0].table_name == "Test DatasetInfo"
-        assert result.data.datasets[0].database_name == "examples"
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 1
+        assert data["datasets"][0]["table_name"] == "Test DatasetInfo"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 1
+        assert len(data["datasets"][0]["metrics"]) == 1
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
 async def test_list_datasets_simple_with_filters(mock_list, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 2
     dataset.table_name = "Sales Dataset"
     dataset.schema = "main"
@@ -465,7 +593,7 @@ async def test_list_datasets_simple_with_filters(mock_list, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/2"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -474,6 +602,25 @@ async def test_list_datasets_simple_with_filters(mock_list, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "sum"
+    metric1.verbose_name = "Sum"
+    metric1.expression = "SUM(value)"
+    metric1.description = "Sum of values"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
     dataset._mapping = {
         'id': dataset.id,
         'table_name': dataset.table_name,
@@ -504,8 +651,15 @@ async def test_list_datasets_simple_with_filters(mock_list, mcp_server):
     filters = [{"col": "table_name", "opr": "sw", "value": "Sales"}, {"col": "schema", "opr": "eq", "value": "main"}]
     async with Client(mcp_server) as client:
         result = await client.call_tool("list_datasets", {"filters": filters})
-        assert result.data.count == 1
-        assert result.data.datasets[0].table_name == "Sales Dataset"
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["datasets"] is not None
+        assert len(data["datasets"]) == 1
+        assert data["datasets"][0]["id"] == 2
+        assert data["datasets"][0]["table_name"] == "Sales Dataset"
+        # Check that columns and metrics are included
+        assert len(data["datasets"][0]["columns"]) == 1
+        assert len(data["datasets"][0]["metrics"]) == 1
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.list')
@@ -520,7 +674,7 @@ async def test_list_datasets_simple_api_error(mock_list, mcp_server):
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.find_by_id')
 async def test_get_dataset_info_success(mock_info, mcp_server):
-    dataset = Mock()
+    dataset = MagicMock()
     dataset.id = 1
     dataset.table_name = "Test DatasetInfo"
     dataset.schema = "main"
@@ -537,7 +691,7 @@ async def test_get_dataset_info_success(mock_info, mcp_server):
     dataset.database_id = 1
     dataset.schema_perm = "[examples].[main]"
     dataset.url = "/tablemodelview/edit/1"
-    dataset.database = Mock()
+    dataset.database = MagicMock()
     dataset.database.database_name = "examples"
     dataset.sql = None
     dataset.main_dttm_col = None
@@ -546,36 +700,38 @@ async def test_get_dataset_info_success(mock_info, mcp_server):
     dataset.params = {}
     dataset.template_params = {}
     dataset.extra = {}
-    dataset._mapping = {
-        'id': dataset.id,
-        'table_name': dataset.table_name,
-        'db_schema': dataset.schema,
-        'database_name': dataset.database.database_name,
-        'description': dataset.description,
-        'changed_by_name': dataset.changed_by_name,
-        'changed_on': dataset.changed_on,
-        'changed_on_humanized': dataset.changed_on_humanized,
-        'created_by_name': dataset.created_by_name,
-        'created_on': dataset.created_on,
-        'created_on_humanized': dataset.created_on_humanized,
-        'tags': dataset.tags,
-        'owners': dataset.owners,
-        'is_virtual': dataset.is_virtual,
-        'database_id': dataset.database_id,
-        'schema_perm': dataset.schema_perm,
-        'url': dataset.url,
-        'sql': dataset.sql,
-        'main_dttm_col': dataset.main_dttm_col,
-        'offset': dataset.offset,
-        'cache_timeout': dataset.cache_timeout,
-        'params': dataset.params,
-        'template_params': dataset.template_params,
-        'extra': dataset.extra,
-    }
-    mock_info.return_value = dataset  # Only the dataset object
+    # Add proper mock columns and metrics
+    col1 = MagicMock()
+    col1.column_name = "id"
+    col1.verbose_name = "ID"
+    col1.type = "INTEGER"
+    col1.is_dttm = False
+    col1.groupby = True
+    col1.filterable = True
+    col1.description = "Primary key"
+    
+    metric1 = MagicMock()
+    metric1.metric_name = "count"
+    metric1.verbose_name = "Count"
+    metric1.expression = "COUNT(*)"
+    metric1.description = "Row count"
+    metric1.d3format = None
+    
+    dataset.columns = [col1]
+    dataset.metrics = [metric1]
+    mock_info.return_value = dataset
     async with Client(mcp_server) as client:
         result = await client.call_tool("get_dataset_info", {"dataset_id": 1})
-        assert result.data["table_name"] == "Test DatasetInfo"
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["id"] == 1
+        assert data["table_name"] == "Test DatasetInfo"
+        assert data["database_name"] == "examples"
+        # Check that columns and metrics are included
+        assert len(data["columns"]) == 1
+        assert len(data["metrics"]) == 1
+        assert data["columns"][0]["column_name"] == "id"
+        assert data["metrics"][0]["metric_name"] == "count"
 
 @pytest.mark.asyncio
 @patch('superset.daos.dataset.DatasetDAO.find_by_id')
@@ -613,3 +769,105 @@ async def test_invalid_filter_column_raises(mcp_server):
         with pytest.raises(fastmcp.exceptions.ToolError) as excinfo:
             await client.call_tool("list_datasets", {"filters": [{"col": "not_a_column", "opr": "eq", "value": "foo"}]})
         assert "Input validation error" in str(excinfo.value)
+
+@pytest.mark.asyncio
+@patch('superset.daos.dataset.DatasetDAO.find_by_id')
+async def test_get_dataset_info_includes_columns_and_metrics(mock_info, mcp_server):
+    dataset = MagicMock()
+    dataset.id = 10
+    dataset.table_name = "Dataset With Columns"
+    dataset.schema = "main"
+    dataset.database = MagicMock()
+    dataset.database.database_name = "examples"
+    dataset.description = "desc"
+    dataset.changed_by_name = "admin"
+    dataset.changed_on = None
+    dataset.changed_on_humanized = None
+    dataset.created_by_name = "admin"
+    dataset.created_on = None
+    dataset.created_on_humanized = None
+    dataset.tags = []
+    dataset.owners = []
+    dataset.is_virtual = False
+    dataset.database_id = 1
+    dataset.schema_perm = "[examples].[main]"
+    dataset.url = "/tablemodelview/edit/10"
+    dataset.sql = None
+    dataset.main_dttm_col = None
+    dataset.offset = 0
+    dataset.cache_timeout = 0
+    dataset.params = {}
+    dataset.template_params = {}
+    dataset.extra = {}
+    dataset.columns = [
+        MagicMock(column_name="col1", verbose_name="Column 1", type="INTEGER", is_dttm=False, groupby=True, filterable=True, description="First column"),
+        MagicMock(column_name="col2", verbose_name="Column 2", type="VARCHAR", is_dttm=False, groupby=False, filterable=True, description="Second column"),
+    ]
+    dataset.metrics = [
+        MagicMock(metric_name="sum_sales", verbose_name="Sum Sales", expression="SUM(sales)", description="Total sales", d3format=None),
+        MagicMock(metric_name="count_orders", verbose_name="Count Orders", expression="COUNT(orders)", description="Order count", d3format=None),
+    ]
+    mock_info.return_value = dataset
+    async with Client(mcp_server) as client:
+        result = await client.call_tool("get_dataset_info", {"dataset_id": 10})
+        assert result.content is not None
+        data = json.loads(result.content[0].text)
+        assert data["table_name"] == "Dataset With Columns"
+        assert data["database_name"] == "examples"
+        # Check that columns and metrics are included
+        assert len(data["columns"]) == 2
+        assert len(data["metrics"]) == 2
+        assert data["columns"][0]["column_name"] == "col1"
+        assert data["columns"][1]["column_name"] == "col2"
+        assert data["metrics"][0]["metric_name"] == "sum_sales"
+        assert data["metrics"][1]["metric_name"] == "count_orders"
+
+@pytest.mark.asyncio
+@patch('superset.daos.dataset.DatasetDAO.list')
+async def test_list_datasets_includes_columns_and_metrics(mock_list, mcp_server):
+    dataset = MagicMock()
+    dataset.id = 11
+    dataset.table_name = "DatasetList With Columns"
+    dataset.schema = "main"
+    dataset.database = MagicMock()
+    dataset.database.database_name = "examples"
+    dataset.description = "desc"
+    dataset.changed_by_name = "admin"
+    dataset.changed_on = None
+    dataset.changed_on_humanized = None
+    dataset.created_by_name = "admin"
+    dataset.created_on = None
+    dataset.created_on_humanized = None
+    dataset.tags = []
+    dataset.owners = []
+    dataset.is_virtual = False
+    dataset.database_id = 1
+    dataset.schema_perm = "[examples].[main]"
+    dataset.url = "/tablemodelview/edit/11"
+    dataset.sql = None
+    dataset.main_dttm_col = None
+    dataset.offset = 0
+    dataset.cache_timeout = 0
+    dataset.params = {}
+    dataset.template_params = {}
+    dataset.extra = {}
+    dataset.columns = [
+        MagicMock(column_name="colA", verbose_name="Column A", type="FLOAT", is_dttm=False, groupby=True, filterable=True, description="A column"),
+    ]
+    dataset.metrics = [
+        MagicMock(metric_name="avg_value", verbose_name="Avg Value", expression="AVG(value)", description="Average value", d3format=None),
+    ]
+    mock_list.return_value = ([dataset], 1)
+    async with Client(mcp_server) as client:
+        result = await client.call_tool("list_datasets", {"page": 1, "page_size": 10})
+        datasets = result.data.datasets
+        assert len(datasets) == 1
+        ds = datasets[0]
+        assert hasattr(ds, "columns")
+        assert hasattr(ds, "metrics")
+        assert isinstance(ds.columns, list)
+        assert isinstance(ds.metrics, list)
+        assert len(ds.columns) == 1
+        assert len(ds.metrics) == 1
+        assert ds.columns[0].column_name == "colA"
+        assert ds.metrics[0].metric_name == "avg_value"