Make sure that optional parameters in the search tool are represented…

ads_mcp/tools/search.py

@@ -27,9 +27,9 @@ def search(
     customer_id: str,
     fields: List[str],
     resource: str,
-    conditions: List[str] = None,
-    orderings: List[str] = None,
-    limit: int = None,
+    conditions: List[str] | None = None,
+    orderings: List[str] | None = None,
+    limit: int | None = None,
 ) -> List[Dict[str, Any]]:
     """Fetches data from the Google Ads API using the search method
 

tests/smoke/golden_tools_list.json

@@ -75,12 +75,19 @@
         "additionalProperties": false,
         "properties": {
           "conditions": {
+            "anyOf": [
+              {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              {
+                "type": "null"
+              }
+            ],
             "default": null,
-            "description": "List of conditions to filter the data, combined using AND clauses",
-            "items": {
-              "type": "string"
-            },
-            "type": "array"
+            "description": "List of conditions to filter the data, combined using AND clauses"
           },
           "customer_id": {
             "description": "The id of the customer",
@@ -94,17 +101,31 @@
             "type": "array"
           },
           "limit": {
+            "anyOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
             "default": null,
-            "description": "The maximum number of rows to return",
-            "type": "integer"
+            "description": "The maximum number of rows to return"
           },
           "orderings": {
+            "anyOf": [
+              {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              {
+                "type": "null"
+              }
+            ],
             "default": null,
-            "description": "How the data is ordered",
-            "items": {
-              "type": "string"
-            },
-            "type": "array"
+            "description": "How the data is ordered"
           },
           "resource": {
             "description": "The resource to return fields from",

tests/smoke/llm_cases.json

@@ -2,100 +2,100 @@
   {
     "prompt": "List the customers I can access.",
     "expected_tool": "list_accessible_customers",
-    "prompt_tokens": 524,
+    "prompt_tokens": 538,
     "output_tokens": 12,
     "model": "gemini-flash-latest",
-    "thought_tokens": 27,
+    "thought_tokens": 61,
     "tool_tokens": 170
   },
   {
     "prompt": "Find campaigns matching 'Test Campaign' for customer {customer_id}.",
     "expected_tool": "search",
-    "prompt_tokens": 538,
-    "output_tokens": 64,
+    "prompt_tokens": 552,
+    "output_tokens": 20,
     "model": "gemini-flash-latest",
-    "thought_tokens": 236,
-    "tool_tokens": 35
+    "thought_tokens": 80,
+    "tool_tokens": 35429
   },
   {
     "prompt": "Show me all my accounts.",
     "expected_tool": "list_accessible_customers",
-    "prompt_tokens": 523,
+    "prompt_tokens": 537,
     "output_tokens": 12,
     "model": "gemini-flash-latest",
-    "thought_tokens": 25,
+    "thought_tokens": 46,
     "tool_tokens": 170
   },
   {
     "prompt": "Which customers do I have access to?",
     "expected_tool": "list_accessible_customers",
-    "prompt_tokens": 525,
+    "prompt_tokens": 539,
     "output_tokens": 12,
     "model": "gemini-flash-latest",
-    "thought_tokens": 29,
+    "thought_tokens": 66,
     "tool_tokens": 170
   },
   {
     "prompt": "Find enabled ad groups for customer {customer_id}.",
     "expected_tool": "search",
-    "prompt_tokens": 535,
+    "prompt_tokens": 549,
     "output_tokens": 22,
     "model": "gemini-flash-latest",
-    "thought_tokens": 152,
-    "tool_tokens": 24555
+    "thought_tokens": 93,
+    "tool_tokens": 24699
   },
   {
     "prompt": "Get keywords for campaign 'Summer Sale' in account {customer_id}.",
     "expected_tool": "search",
-    "prompt_tokens": 539,
-    "output_tokens": 58,
+    "prompt_tokens": 553,
+    "output_tokens": 20,
     "model": "gemini-flash-latest",
-    "thought_tokens": 238,
-    "tool_tokens": 35
+    "thought_tokens": 201,
+    "tool_tokens": 35429
   },
   {
     "prompt": "Show me the metrics for customer {customer_id}.",
     "expected_tool": "search",
-    "prompt_tokens": 535,
+    "prompt_tokens": 549,
     "output_tokens": 20,
     "model": "gemini-flash-latest",
-    "thought_tokens": 70,
-    "tool_tokens": 22505
+    "thought_tokens": 150,
+    "tool_tokens": 22703
   },
   {
     "prompt": "Generate a daily report of clicks for all active campaigns in account {customer_id}.",
     "expected_tool": "search",
-    "prompt_tokens": 541,
-    "output_tokens": 51,
-    "thought_tokens": 198,
+    "prompt_tokens": 555,
+    "output_tokens": 20,
+    "thought_tokens": 88,
     "model": "gemini-flash-latest",
-    "tool_tokens": 70
+    "tool_tokens": 35429
   },
   {
     "prompt": "What fields are available for the campaign resource?",
     "expected_tool": "get_resource_metadata",
-    "prompt_tokens": 526,
+    "prompt_tokens": 540,
     "output_tokens": 20,
-    "thought_tokens": 34,
+    "thought_tokens": 87,
     "model": "gemini-flash-latest",
-    "tool_tokens": 35231
+    "tool_tokens": 35429
   },
   {
     "prompt": "Find metrics compatible with ad_group.",
     "expected_tool": "get_resource_metadata",
-    "prompt_tokens": 525,
+    "prompt_tokens": 539,
     "output_tokens": 22,
-    "thought_tokens": 32,
+    "thought_tokens": 81,
     "model": "gemini-flash-latest",
-    "tool_tokens": 24555
+    "tool_tokens": 24699
   },
   {
     "prompt": "What segments can I select with the customer resource?",
     "expected_tool": "get_resource_metadata",
-    "prompt_tokens": 527,
+    "prompt_tokens": 541,
     "output_tokens": 20,
-    "thought_tokens": 38,
+    "thought_tokens": 90,
     "model": "gemini-flash-latest",
-    "tool_tokens": 22505
+    "tool_tokens": 22703
   }
 ]

tests/tools/schema_test.py

@@ -0,0 +1,75 @@
+# Copyright 2026 Google LLC.
+#
+# 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.
+
+"""Tests for tool schema correctness and type safety."""
+
+import unittest
+from ads_mcp.coordinator import mcp
+
+# Import server to ensure all tools are registered on the mcp object
+from ads_mcp import server  # noqa: F401
+
+
+class TestToolSchemas(unittest.IsolatedAsyncioTestCase):
+    """Verifies that tool schemas are properly defined and prevent Zod errors."""
+
+    async def test_optional_parameters_allow_null(self):
+        """Verifies that any tool parameter with a default of None allows 'null' in its schema.
+
+        This prevents 'Expected array, received string' or similar client-side Zod validation
+        failures caused by schema type contradictions (e.g. type 'array' but default is 'null').
+        """
+        tools = await mcp.list_tools()
+        self.assertGreater(
+            len(tools), 0, "No tools are registered on the server"
+        )
+
+        for tool in tools:
+            input_schema = tool.parameters
+            properties = input_schema.get("properties", {})
+            for param_name, param_schema in properties.items():
+                # If a parameter has a default value of None (JSON null), the schema must permit null
+                if (
+                    "default" in param_schema
+                    and param_schema["default"] is None
+                ):
+                    has_null_type = False
+
+                    # Case 1: Schema uses anyOf (standard for Pydantic unions)
+                    if "anyOf" in param_schema:
+                        for option in param_schema["anyOf"]:
+                            if option.get("type") == "null":
+                                has_null_type = True
+                                break
+
+                    # Case 2: Schema uses oneOf
+                    elif "oneOf" in param_schema:
+                        for option in param_schema["oneOf"]:
+                            if option.get("type") == "null":
+                                has_null_type = True
+                                break
+
+                    # Case 3: Schema has list-based types or direct type 'null'
+                    elif "type" in param_schema:
+                        t = param_schema["type"]
+                        if t == "null":
+                            has_null_type = True
+                        elif isinstance(t, list) and "null" in t:
+                            has_null_type = True
+
+                    self.assertTrue(
+                        has_null_type,
+                        f"Tool '{tool.name}' parameter '{param_name}' has default=None, "
+                        f"but its JSON schema does not permit 'null'. Schema: {param_schema}",
+                    )