fix: remove incorrect default.tools fallback from _parse_tools call sites

The variation call already incorporates the default via default_dict;
applying a second-level default here is incorrect.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jsonbailey

packages/sdk/server-ai/src/ldai/client.py

@@ -112,8 +112,7 @@ def _completion_config(
             key, context, default.to_dict(), variables
         )
 
-        tools_data = variation.get('tools')
-        tools = _parse_tools(tools_data) if tools_data is not None else default.tools
+        tools = _parse_tools(variation.get('tools'))
 
         config = AICompletionConfig(
             key=key,
@@ -921,8 +920,7 @@ def __evaluate_agent(
         # For agents, prioritize instructions over messages
         final_instructions = instructions if instructions is not None else default.instructions
 
-        tools_data = variation.get('tools')
-        tools = _parse_tools(tools_data) if tools_data is not None else default.tools
+        tools = _parse_tools(variation.get('tools'))
 
         return AIAgentConfig(
             key=key,

packages/sdk/server-ai/tests/test_tools.py

@@ -92,15 +92,13 @@ def test_completion_config_tools_none_when_not_in_variation(client, context):
     assert result.tools is None
 
 
-def test_completion_config_falls_back_to_default_tools(client, context):
+def test_completion_config_tools_none_when_variation_has_no_tools(client, context):
     default_tool = LDTool(name='default-tool', type='function', custom_parameters={'priority': 'high'})
     default = AICompletionConfigDefault(tools={'default-tool': default_tool})
 
     result = client.completion_config('completion-no-tools', context, default)
 
-    assert result.tools is not None
-    assert 'default-tool' in result.tools
-    assert result.tools['default-tool'].custom_parameters == {'priority': 'high'}
+    assert result.tools is None
 
 
 def test_agent_config_includes_tools_from_variation(client, context):