fix: Disable tool caching for skill toolset

Skill toolset's tools can change dynamically within a single invocation (when a skill is loaded)

Co-authored-by: Kathy Wu <wukathy@google.com>
PiperOrigin-RevId: 893666326

Author: wukath

src/google/adk/tools/base_toolset.py

@@ -82,6 +82,7 @@ def __init__(
     self.tool_name_prefix = tool_name_prefix
     self._cached_invocation_id: Optional[str] = None
     self._cached_prefixed_tools: Optional[list[BaseTool]] = None
+    self._use_invocation_cache = True
 
   @abstractmethod
   async def get_tools(
@@ -117,7 +118,8 @@ async def get_tools_with_prefix(
     invocation_id = readonly_context.invocation_id if readonly_context else None
 
     if (
-        self._cached_prefixed_tools is not None
+        self._use_invocation_cache
+        and self._cached_prefixed_tools is not None
         and self._cached_invocation_id == invocation_id
     ):
       return self._cached_prefixed_tools

src/google/adk/tools/skill_toolset.py

@@ -700,6 +700,7 @@ def __init__(
     self._skills = {skill.name: skill for skill in skills}
     self._code_executor = code_executor
     self._script_timeout = script_timeout
+    self._use_invocation_cache = False
 
     self._provided_tools_by_name = {}
     self._provided_toolsets = []

tests/unittests/tools/test_base_toolset.py

@@ -438,3 +438,13 @@ async def test_get_tools_with_prefix_caching():
   assert len(tools3) == 1
   assert tools3 is not tools1  # Should be a new list instance
   assert tools3[0].name == 'test_tool1'
+
+  # Test disabling caching
+  toolset._use_invocation_cache = False
+  tools4 = await toolset.get_tools_with_prefix(
+      readonly_context=readonly_context2
+  )
+  tools5 = await toolset.get_tools_with_prefix(
+      readonly_context=readonly_context2
+  )
+  assert tools4 is not tools5

tests/unittests/tools/test_skill_toolset.py

@@ -1340,16 +1340,17 @@ def my_func():
 
   ctx = _make_tool_context_with_agent()
   # Initial tools (only core)
-  tools = await toolset.get_tools(readonly_context=ctx)
-  assert len(tools) == 4
+  tools1 = await toolset.get_tools_with_prefix(readonly_context=ctx)
+  assert len(tools1) == 4
 
   # Activate skills
   load_tool = skill_toolset.LoadSkillTool(toolset)
   await load_tool.run_async(args={"name": "skill1"}, tool_context=ctx)
   await load_tool.run_async(args={"name": "skill2"}, tool_context=ctx)
 
   # Dynamic tools should now be resolved
-  tools = await toolset.get_tools(readonly_context=ctx)
+  tools = await toolset.get_tools_with_prefix(readonly_context=ctx)
+  assert tools is not tools1
   tool_names = {t.name for t in tools}
 
   # Core tools