diff --git a/src/google/adk/agents/callback_context.py b/src/google/adk/agents/callback_context.py
index 93b785c..9d6e311 100644
--- a/src/google/adk/agents/callback_context.py
+++ b/src/google/adk/agents/callback_context.py
@@ -65,7 +65,7 @@ class CallbackContext(ReadonlyContext):
     """The user content that started this invocation. READONLY field."""
     return self._invocation_context.user_content
 
-  def load_artifact(
+  async def load_artifact(
       self, filename: str, version: Optional[int] = None
   ) -> Optional[types.Part]:
     """Loads an artifact attached to the current session.
@@ -80,7 +80,7 @@ class CallbackContext(ReadonlyContext):
     """
     if self._invocation_context.artifact_service is None:
       raise ValueError("Artifact service is not initialized.")
-    return self._invocation_context.artifact_service.load_artifact(
+    return await self._invocation_context.artifact_service.load_artifact(
         app_name=self._invocation_context.app_name,
         user_id=self._invocation_context.user_id,
         session_id=self._invocation_context.session.id,
@@ -88,7 +88,7 @@ class CallbackContext(ReadonlyContext):
         version=version,
     )
 
-  def save_artifact(self, filename: str, artifact: types.Part) -> int:
+  async def save_artifact(self, filename: str, artifact: types.Part) -> int:
     """Saves an artifact and records it as delta for the current session.
 
     Args:
@@ -100,7 +100,7 @@ class CallbackContext(ReadonlyContext):
     """
     if self._invocation_context.artifact_service is None:
       raise ValueError("Artifact service is not initialized.")
-    version = self._invocation_context.artifact_service.save_artifact(
+    version = await self._invocation_context.artifact_service.save_artifact(
         app_name=self._invocation_context.app_name,
         user_id=self._invocation_context.user_id,
         session_id=self._invocation_context.session.id,
diff --git a/src/google/adk/artifacts/base_artifact_service.py b/src/google/adk/artifacts/base_artifact_service.py
index 0af9146..8d14fcb 100644
--- a/src/google/adk/artifacts/base_artifact_service.py
+++ b/src/google/adk/artifacts/base_artifact_service.py
@@ -25,7 +25,7 @@ class BaseArtifactService(ABC):
   """Abstract base class for artifact services."""
 
   @abstractmethod
-  def save_artifact(
+  async def save_artifact(
       self,
       *,
       app_name: str,
@@ -53,7 +53,7 @@ class BaseArtifactService(ABC):
     """
 
   @abstractmethod
-  def load_artifact(
+  async def load_artifact(
       self,
       *,
       app_name: str,
@@ -81,7 +81,7 @@ class BaseArtifactService(ABC):
     pass
 
   @abstractmethod
-  def list_artifact_keys(
+  async def list_artifact_keys(
       self, *, app_name: str, user_id: str, session_id: str
   ) -> list[str]:
     """Lists all the artifact filenames within a session.
@@ -97,7 +97,7 @@ class BaseArtifactService(ABC):
     pass
 
   @abstractmethod
-  def delete_artifact(
+  async def delete_artifact(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> None:
     """Deletes an artifact.
@@ -111,7 +111,7 @@ class BaseArtifactService(ABC):
     pass
 
   @abstractmethod
-  def list_versions(
+  async def list_versions(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> list[int]:
     """Lists all versions of an artifact.
diff --git a/src/google/adk/artifacts/gcs_artifact_service.py b/src/google/adk/artifacts/gcs_artifact_service.py
index 279d5e0..8adbfe5 100644
--- a/src/google/adk/artifacts/gcs_artifact_service.py
+++ b/src/google/adk/artifacts/gcs_artifact_service.py
@@ -77,7 +77,7 @@ class GcsArtifactService(BaseArtifactService):
     return f"{app_name}/{user_id}/{session_id}/{filename}/{version}"
 
   @override
-  def save_artifact(
+  async def save_artifact(
       self,
       *,
       app_name: str,
@@ -86,7 +86,7 @@ class GcsArtifactService(BaseArtifactService):
       filename: str,
       artifact: types.Part,
   ) -> int:
-    versions = self.list_versions(
+    versions = await self.list_versions(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -107,7 +107,7 @@ class GcsArtifactService(BaseArtifactService):
     return version
 
   @override
-  def load_artifact(
+  async def load_artifact(
       self,
       *,
       app_name: str,
@@ -117,7 +117,7 @@ class GcsArtifactService(BaseArtifactService):
       version: Optional[int] = None,
   ) -> Optional[types.Part]:
     if version is None:
-      versions = self.list_versions(
+      versions = await self.list_versions(
           app_name=app_name,
           user_id=user_id,
           session_id=session_id,
@@ -141,7 +141,7 @@ class GcsArtifactService(BaseArtifactService):
     return artifact
 
   @override
-  def list_artifact_keys(
+  async def list_artifact_keys(
       self, *, app_name: str, user_id: str, session_id: str
   ) -> list[str]:
     filenames = set()
@@ -165,10 +165,10 @@ class GcsArtifactService(BaseArtifactService):
     return sorted(list(filenames))
 
   @override
-  def delete_artifact(
+  async def delete_artifact(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> None:
-    versions = self.list_versions(
+    versions = await self.list_versions(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -183,7 +183,7 @@ class GcsArtifactService(BaseArtifactService):
     return
 
   @override
-  def list_versions(
+  async def list_versions(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> list[int]:
     prefix = self._get_blob_name(app_name, user_id, session_id, filename, "")
diff --git a/src/google/adk/artifacts/in_memory_artifact_service.py b/src/google/adk/artifacts/in_memory_artifact_service.py
index 8c886f6..fcfb881 100644
--- a/src/google/adk/artifacts/in_memory_artifact_service.py
+++ b/src/google/adk/artifacts/in_memory_artifact_service.py
@@ -63,7 +63,7 @@ class InMemoryArtifactService(BaseArtifactService, BaseModel):
     return f"{app_name}/{user_id}/{session_id}/{filename}"
 
   @override
-  def save_artifact(
+  async def save_artifact(
       self,
       *,
       app_name: str,
@@ -80,7 +80,7 @@ class InMemoryArtifactService(BaseArtifactService, BaseModel):
     return version
 
   @override
-  def load_artifact(
+  async def load_artifact(
       self,
       *,
       app_name: str,
@@ -98,7 +98,7 @@ class InMemoryArtifactService(BaseArtifactService, BaseModel):
     return versions[version]
 
   @override
-  def list_artifact_keys(
+  async def list_artifact_keys(
       self, *, app_name: str, user_id: str, session_id: str
   ) -> list[str]:
     session_prefix = f"{app_name}/{user_id}/{session_id}/"
@@ -114,7 +114,7 @@ class InMemoryArtifactService(BaseArtifactService, BaseModel):
     return sorted(filenames)
 
   @override
-  def delete_artifact(
+  async def delete_artifact(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> None:
     path = self._artifact_path(app_name, user_id, session_id, filename)
@@ -123,7 +123,7 @@ class InMemoryArtifactService(BaseArtifactService, BaseModel):
     self.artifacts.pop(path, None)
 
   @override
-  def list_versions(
+  async def list_versions(
       self, *, app_name: str, user_id: str, session_id: str, filename: str
   ) -> list[int]:
     path = self._artifact_path(app_name, user_id, session_id, filename)
diff --git a/src/google/adk/cli/fast_api.py b/src/google/adk/cli/fast_api.py
index a7747a1..ed663a5 100644
--- a/src/google/adk/cli/fast_api.py
+++ b/src/google/adk/cli/fast_api.py
@@ -503,7 +503,7 @@ def get_fast_api_app(
       "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts/{artifact_name}",
       response_model_exclude_none=True,
   )
-  def load_artifact(
+  async def load_artifact(
       app_name: str,
       user_id: str,
       session_id: str,
@@ -511,7 +511,7 @@ def get_fast_api_app(
       version: Optional[int] = Query(None),
   ) -> Optional[types.Part]:
     app_name = agent_engine_id if agent_engine_id else app_name
-    artifact = artifact_service.load_artifact(
+    artifact = await artifact_service.load_artifact(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -526,7 +526,7 @@ def get_fast_api_app(
       "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts/{artifact_name}/versions/{version_id}",
       response_model_exclude_none=True,
   )
-  def load_artifact_version(
+  async def load_artifact_version(
       app_name: str,
       user_id: str,
       session_id: str,
@@ -534,7 +534,7 @@ def get_fast_api_app(
       version_id: int,
   ) -> Optional[types.Part]:
     app_name = agent_engine_id if agent_engine_id else app_name
-    artifact = artifact_service.load_artifact(
+    artifact = await artifact_service.load_artifact(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -549,11 +549,11 @@ def get_fast_api_app(
       "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts",
       response_model_exclude_none=True,
   )
-  def list_artifact_names(
+  async def list_artifact_names(
       app_name: str, user_id: str, session_id: str
   ) -> list[str]:
     app_name = agent_engine_id if agent_engine_id else app_name
-    return artifact_service.list_artifact_keys(
+    return await artifact_service.list_artifact_keys(
         app_name=app_name, user_id=user_id, session_id=session_id
     )
 
@@ -561,11 +561,11 @@ def get_fast_api_app(
       "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts/{artifact_name}/versions",
       response_model_exclude_none=True,
   )
-  def list_artifact_versions(
+  async def list_artifact_versions(
       app_name: str, user_id: str, session_id: str, artifact_name: str
   ) -> list[int]:
     app_name = agent_engine_id if agent_engine_id else app_name
-    return artifact_service.list_versions(
+    return await artifact_service.list_versions(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -575,11 +575,11 @@ def get_fast_api_app(
   @app.delete(
       "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts/{artifact_name}",
   )
-  def delete_artifact(
+  async def delete_artifact(
       app_name: str, user_id: str, session_id: str, artifact_name: str
   ):
     app_name = agent_engine_id if agent_engine_id else app_name
-    artifact_service.delete_artifact(
+    await artifact_service.delete_artifact(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
diff --git a/src/google/adk/flows/llm_flows/_code_execution.py b/src/google/adk/flows/llm_flows/_code_execution.py
index 7ca57af..8a6a56e 100644
--- a/src/google/adk/flows/llm_flows/_code_execution.py
+++ b/src/google/adk/flows/llm_flows/_code_execution.py
@@ -122,7 +122,7 @@ class _CodeExecutionRequestProcessor(BaseLlmRequestProcessor):
     if not invocation_context.agent.code_executor:
       return
 
-    for event in _run_pre_processor(invocation_context, llm_request):
+    async for event in _run_pre_processor(invocation_context, llm_request):
       yield event
 
     # Convert the code execution parts to text parts.
@@ -159,10 +159,10 @@ class _CodeExecutionResponseProcessor(BaseLlmResponseProcessor):
 response_processor = _CodeExecutionResponseProcessor()
 
 
-def _run_pre_processor(
+async def _run_pre_processor(
     invocation_context: InvocationContext,
     llm_request: LlmRequest,
-) -> Generator[Event, None, None]:
+) -> AsyncGenerator[Event, None]:
   """Pre-process the user message by adding the user message to the Colab notebook."""
   from ...agents.llm_agent import LlmAgent
 
@@ -242,7 +242,7 @@ def _run_pre_processor(
     code_executor_context.add_processed_file_names([file.name])
 
     # Emit the execution result, and add it to the LLM request.
-    execution_result_event = _post_process_code_execution_result(
+    execution_result_event = await _post_process_code_execution_result(
         invocation_context, code_executor_context, code_execution_result
     )
     yield execution_result_event
@@ -375,7 +375,7 @@ def _get_or_set_execution_id(
   return execution_id
 
 
-def _post_process_code_execution_result(
+async def _post_process_code_execution_result(
     invocation_context: InvocationContext,
     code_executor_context: CodeExecutorContext,
     code_execution_result: CodeExecutionResult,
@@ -406,7 +406,7 @@ def _post_process_code_execution_result(
 
   # Handle output files.
   for output_file in code_execution_result.output_files:
-    version = invocation_context.artifact_service.save_artifact(
+    version = await invocation_context.artifact_service.save_artifact(
         app_name=invocation_context.app_name,
         user_id=invocation_context.user_id,
         session_id=invocation_context.session.id,
diff --git a/src/google/adk/flows/llm_flows/instructions.py b/src/google/adk/flows/llm_flows/instructions.py
index 860240d..041c867 100644
--- a/src/google/adk/flows/llm_flows/instructions.py
+++ b/src/google/adk/flows/llm_flows/instructions.py
@@ -56,13 +56,13 @@ class _InstructionsLlmRequestProcessor(BaseLlmRequestProcessor):
       raw_si = root_agent.canonical_global_instruction(
           ReadonlyContext(invocation_context)
       )
-      si = _populate_values(raw_si, invocation_context)
+      si = await _populate_values(raw_si, invocation_context)
       llm_request.append_instructions([si])
 
     # Appends agent instructions if set.
     if agent.instruction:  # not empty str
       raw_si = agent.canonical_instruction(ReadonlyContext(invocation_context))
-      si = _populate_values(raw_si, invocation_context)
+      si = await _populate_values(raw_si, invocation_context)
       llm_request.append_instructions([si])
 
     # Maintain async generator behavior
@@ -73,13 +73,24 @@ class _InstructionsLlmRequestProcessor(BaseLlmRequestProcessor):
 request_processor = _InstructionsLlmRequestProcessor()
 
 
-def _populate_values(
+async def _populate_values(
     instruction_template: str,
     context: InvocationContext,
 ) -> str:
   """Populates values in the instruction template, e.g. state, artifact, etc."""
 
-  def _replace_match(match) -> str:
+  async def _async_sub(pattern, repl_async_fn, string) -> str:
+    result = []
+    last_end = 0
+    for match in re.finditer(pattern, string):
+      result.append(string[last_end : match.start()])
+      replacement = await repl_async_fn(match)
+      result.append(replacement)
+      last_end = match.end()
+    result.append(string[last_end:])
+    return ''.join(result)
+
+  async def _replace_match(match) -> str:
     var_name = match.group().lstrip('{').rstrip('}').strip()
     optional = False
     if var_name.endswith('?'):
@@ -89,7 +100,7 @@ def _populate_values(
       var_name = var_name.removeprefix('artifact.')
       if context.artifact_service is None:
         raise ValueError('Artifact service is not initialized.')
-      artifact = context.artifact_service.load_artifact(
+      artifact = await context.artifact_service.load_artifact(
           app_name=context.session.app_name,
           user_id=context.session.user_id,
           session_id=context.session.id,
@@ -109,7 +120,7 @@ def _populate_values(
         else:
           raise KeyError(f'Context variable not found: `{var_name}`.')
 
-  return re.sub(r'{+[^{}]*}+', _replace_match, instruction_template)
+  return await _async_sub(r'{+[^{}]*}+', _replace_match, instruction_template)
 
 
 def _is_valid_state_name(var_name):
diff --git a/src/google/adk/runners.py b/src/google/adk/runners.py
index 15b1ee2..1ec8631 100644
--- a/src/google/adk/runners.py
+++ b/src/google/adk/runners.py
@@ -186,7 +186,7 @@ class Runner:
       root_agent = self.agent
 
       if new_message:
-        self._append_new_message_to_session(
+        await self._append_new_message_to_session(
             session,
             new_message,
             invocation_context,
@@ -199,7 +199,7 @@ class Runner:
           self.session_service.append_event(session=session, event=event)
         yield event
 
-  def _append_new_message_to_session(
+  async def _append_new_message_to_session(
       self,
       session: Session,
       new_message: types.Content,
@@ -225,7 +225,7 @@ class Runner:
         if part.inline_data is None:
           continue
         file_name = f'artifact_{invocation_context.invocation_id}_{i}'
-        self.artifact_service.save_artifact(
+        await self.artifact_service.save_artifact(
             app_name=self.app_name,
             user_id=session.user_id,
             session_id=session.id,
diff --git a/src/google/adk/tools/agent_tool.py b/src/google/adk/tools/agent_tool.py
index 3efafdb..aab9ae2 100644
--- a/src/google/adk/tools/agent_tool.py
+++ b/src/google/adk/tools/agent_tool.py
@@ -146,18 +146,20 @@ class AgentTool(BaseTool):
 
     if runner.artifact_service:
       # Forward all artifacts to parent session.
-      for artifact_name in runner.artifact_service.list_artifact_keys(
+      async for artifact_name in runner.artifact_service.list_artifact_keys(
           app_name=session.app_name,
           user_id=session.user_id,
           session_id=session.id,
       ):
-        if artifact := runner.artifact_service.load_artifact(
+        if artifact := await runner.artifact_service.load_artifact(
             app_name=session.app_name,
             user_id=session.user_id,
             session_id=session.id,
             filename=artifact_name,
         ):
-          tool_context.save_artifact(filename=artifact_name, artifact=artifact)
+          await tool_context.save_artifact(
+              filename=artifact_name, artifact=artifact
+          )
 
     if (
         not last_event
diff --git a/src/google/adk/tools/load_artifacts_tool.py b/src/google/adk/tools/load_artifacts_tool.py
index bee650f..db28aef 100644
--- a/src/google/adk/tools/load_artifacts_tool.py
+++ b/src/google/adk/tools/load_artifacts_tool.py
@@ -69,14 +69,14 @@ class LoadArtifactsTool(BaseTool):
         tool_context=tool_context,
         llm_request=llm_request,
     )
-    self._append_artifacts_to_llm_request(
+    await self._append_artifacts_to_llm_request(
         tool_context=tool_context, llm_request=llm_request
     )
 
-  def _append_artifacts_to_llm_request(
+  async def _append_artifacts_to_llm_request(
       self, *, tool_context: ToolContext, llm_request: LlmRequest
   ):
-    artifact_names = tool_context.list_artifacts()
+    artifact_names = await tool_context.list_artifacts()
     if not artifact_names:
       return
 
@@ -96,7 +96,7 @@ class LoadArtifactsTool(BaseTool):
       if function_response and function_response.name == 'load_artifacts':
         artifact_names = function_response.response['artifact_names']
         for artifact_name in artifact_names:
-          artifact = tool_context.load_artifact(artifact_name)
+          artifact = await tool_context.load_artifact(artifact_name)
           llm_request.contents.append(
               types.Content(
                   role='user',
diff --git a/src/google/adk/tools/tool_context.py b/src/google/adk/tools/tool_context.py
index ad8fce8..e99d42c 100644
--- a/src/google/adk/tools/tool_context.py
+++ b/src/google/adk/tools/tool_context.py
@@ -69,11 +69,11 @@ class ToolContext(CallbackContext):
   def get_auth_response(self, auth_config: AuthConfig) -> AuthCredential:
     return AuthHandler(auth_config).get_auth_response(self.state)
 
-  def list_artifacts(self) -> list[str]:
+  async def list_artifacts(self) -> list[str]:
     """Lists the filenames of the artifacts attached to the current session."""
     if self._invocation_context.artifact_service is None:
       raise ValueError('Artifact service is not initialized.')
-    return self._invocation_context.artifact_service.list_artifact_keys(
+    return await self._invocation_context.artifact_service.list_artifact_keys(
         app_name=self._invocation_context.app_name,
         user_id=self._invocation_context.user_id,
         session_id=self._invocation_context.session.id,
diff --git a/tests/unittests/artifacts/test_artifact_service.py b/tests/unittests/artifacts/test_artifact_service.py
index e8ce497..6f8ef0b 100644
--- a/tests/unittests/artifacts/test_artifact_service.py
+++ b/tests/unittests/artifacts/test_artifact_service.py
@@ -152,13 +152,14 @@ def get_artifact_service(
   return InMemoryArtifactService()
 
 
+@pytest.mark.asyncio
 @pytest.mark.parametrize(
     "service_type", [ArtifactServiceType.IN_MEMORY, ArtifactServiceType.GCS]
 )
-def test_load_empty(service_type):
+async def test_load_empty(service_type):
   """Tests loading an artifact when none exists."""
   artifact_service = get_artifact_service(service_type)
-  assert not artifact_service.load_artifact(
+  assert not await artifact_service.load_artifact(
       app_name="test_app",
       user_id="test_user",
       session_id="session_id",
@@ -166,10 +167,11 @@ def test_load_empty(service_type):
   )
 
 
+@pytest.mark.asyncio
 @pytest.mark.parametrize(
     "service_type", [ArtifactServiceType.IN_MEMORY, ArtifactServiceType.GCS]
 )
-def test_save_load_delete(service_type):
+async def test_save_load_delete(service_type):
   """Tests saving, loading, and deleting an artifact."""
   artifact_service = get_artifact_service(service_type)
   artifact = types.Part.from_bytes(data=b"test_data", mime_type="text/plain")
@@ -178,7 +180,7 @@ def test_save_load_delete(service_type):
   session_id = "123"
   filename = "file456"
 
-  artifact_service.save_artifact(
+  await artifact_service.save_artifact(
       app_name=app_name,
       user_id=user_id,
       session_id=session_id,
@@ -186,7 +188,7 @@ def test_save_load_delete(service_type):
       artifact=artifact,
   )
   assert (
-      artifact_service.load_artifact(
+      await artifact_service.load_artifact(
           app_name=app_name,
           user_id=user_id,
           session_id=session_id,
@@ -195,13 +197,13 @@ def test_save_load_delete(service_type):
       == artifact
   )
 
-  artifact_service.delete_artifact(
+  await artifact_service.delete_artifact(
       app_name=app_name,
       user_id=user_id,
       session_id=session_id,
       filename=filename,
   )
-  assert not artifact_service.load_artifact(
+  assert not await artifact_service.load_artifact(
       app_name=app_name,
       user_id=user_id,
       session_id=session_id,
@@ -209,10 +211,11 @@ def test_save_load_delete(service_type):
   )
 
 
+@pytest.mark.asyncio
 @pytest.mark.parametrize(
     "service_type", [ArtifactServiceType.IN_MEMORY, ArtifactServiceType.GCS]
 )
-def test_list_keys(service_type):
+async def test_list_keys(service_type):
   """Tests listing keys in the artifact service."""
   artifact_service = get_artifact_service(service_type)
   artifact = types.Part.from_bytes(data=b"test_data", mime_type="text/plain")
@@ -223,7 +226,7 @@ def test_list_keys(service_type):
   filenames = [filename + str(i) for i in range(5)]
 
   for f in filenames:
-    artifact_service.save_artifact(
+    await artifact_service.save_artifact(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -232,17 +235,18 @@ def test_list_keys(service_type):
     )
 
   assert (
-      artifact_service.list_artifact_keys(
+      await artifact_service.list_artifact_keys(
           app_name=app_name, user_id=user_id, session_id=session_id
       )
       == filenames
   )
 
 
+@pytest.mark.asyncio
 @pytest.mark.parametrize(
     "service_type", [ArtifactServiceType.IN_MEMORY, ArtifactServiceType.GCS]
 )
-def test_list_versions(service_type):
+async def test_list_versions(service_type):
   """Tests listing versions of an artifact."""
   artifact_service = get_artifact_service(service_type)
 
@@ -258,7 +262,7 @@ def test_list_versions(service_type):
   ]
 
   for i in range(3):
-    artifact_service.save_artifact(
+    await artifact_service.save_artifact(
         app_name=app_name,
         user_id=user_id,
         session_id=session_id,
@@ -266,7 +270,7 @@ def test_list_versions(service_type):
         artifact=versions[i],
     )
 
-  response_versions = artifact_service.list_versions(
+  response_versions = await artifact_service.list_versions(
       app_name=app_name,
       user_id=user_id,
       session_id=session_id,