add toolset base class and allow llm agent to accept toolset as tools

PiperOrigin-RevId: 756605470

src/google/adk/tools/base_toolset.py

@@ -0,0 +1,56 @@
+from abc import ABC
+from abc import abstractmethod
+from typing import Protocol
+
+from google.adk.agents.readonly_context import ReadonlyContext
+from google.adk.tools.base_tool import BaseTool
+
+
+class ToolPredicate(Protocol):
+  """Base class for a predicate that defines the interface to decide whether a
+
+  tool should be exposed to LLM. Toolset implementer could consider whether to
+  accept such instance in the toolset's constructor and apply the predicate in
+  get_tools method.
+  """
+
+  def __call__(
+      self, tool: BaseTool, readonly_context: ReadonlyContext = None
+  ) -> bool:
+    """Decide whether the passed-in tool should be exposed to LLM based on the
+
+    current context. True if the tool is usable by the LLM.
+
+    It's used to filter tools in the toolset.
+    """
+
+
+class BaseToolset(ABC):
+  """Base class for toolset.
+
+  A toolset is a collection of tools that can be used by an agent.
+  """
+
+  @abstractmethod
+  async def get_tools(
+      self, readony_context: ReadonlyContext = None
+  ) -> list[BaseTool]:
+    """Return all tools in the toolset based on the provided context.
+
+    Args:
+      readony_context (ReadonlyContext, optional): Context used to filter tools
+        available to the agent. If None, all tools in the toolset are returned.
+
+    Returns:
+      list[BaseTool]: A list of tools available under the specified context.
+    """
+
+  @abstractmethod
+  async def close(self) -> None:
+    """Performs cleanup and releases resources held by the toolset.
+
+    NOTE: This method is invoked, for example, at the end of an agent server's
+    lifecycle or when the toolset is no longer needed. Implementations
+    should ensure that any open connections, files, or other managed
+    resources are properly released to prevent leaks.
+    """