diff --git a/src/google/adk/tools/load_artifacts_tool.py b/src/google/adk/tools/load_artifacts_tool.py
index dbdc1f26f2..8f82d4df7a 100644
--- a/src/google/adk/tools/load_artifacts_tool.py
+++ b/src/google/adk/tools/load_artifacts_tool.py
@@ -24,6 +24,8 @@
 from google.genai import types
 from typing_extensions import override
 
+from ..features import FeatureName
+from ..features import is_feature_enabled
 from .base_tool import BaseTool
 
 # MIME types Gemini accepts for inline data in requests.
@@ -132,6 +134,20 @@ def __init__(self):
     )
 
   def _get_declaration(self) -> types.FunctionDeclaration | None:
+    if is_feature_enabled(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL):
+      return types.FunctionDeclaration(
+          name=self.name,
+          description=self.description,
+          parameters_json_schema={
+              'type': 'object',
+              'properties': {
+                  'artifact_names': {
+                      'type': 'array',
+                      'items': {'type': 'string'},
+                  },
+              },
+          },
+      )
     return types.FunctionDeclaration(
         name=self.name,
         description=self.description,
diff --git a/src/google/adk/tools/load_memory_tool.py b/src/google/adk/tools/load_memory_tool.py
index 8410e41141..66e2ffabc3 100644
--- a/src/google/adk/tools/load_memory_tool.py
+++ b/src/google/adk/tools/load_memory_tool.py
@@ -21,6 +21,8 @@
 from pydantic import Field
 from typing_extensions import override
 
+from ..features import FeatureName
+from ..features import is_feature_enabled
 from ..memory.memory_entry import MemoryEntry
 from .function_tool import FunctionTool
 from .tool_context import ToolContext
@@ -59,6 +61,18 @@ def __init__(self):
 
   @override
   def _get_declaration(self) -> types.FunctionDeclaration | None:
+    if is_feature_enabled(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL):
+      return types.FunctionDeclaration(
+          name=self.name,
+          description=self.description,
+          parameters_json_schema={
+              'type': 'object',
+              'properties': {
+                  'query': {'type': 'string'},
+              },
+              'required': ['query'],
+          },
+      )
     return types.FunctionDeclaration(
         name=self.name,
         description=self.description,
diff --git a/src/google/adk/tools/retrieval/base_retrieval_tool.py b/src/google/adk/tools/retrieval/base_retrieval_tool.py
index 64f3ec91db..f101be9de3 100644
--- a/src/google/adk/tools/retrieval/base_retrieval_tool.py
+++ b/src/google/adk/tools/retrieval/base_retrieval_tool.py
@@ -12,9 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 from google.genai import types
 from typing_extensions import override
 
+from ...features import FeatureName
+from ...features import is_feature_enabled
 from ..base_tool import BaseTool
 
 
@@ -22,6 +26,20 @@ class BaseRetrievalTool(BaseTool):
 
   @override
   def _get_declaration(self) -> types.FunctionDeclaration:
+    if is_feature_enabled(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL):
+      return types.FunctionDeclaration(
+          name=self.name,
+          description=self.description,
+          parameters_json_schema={
+              'type': 'object',
+              'properties': {
+                  'query': {
+                      'type': 'string',
+                      'description': 'The query to retrieve.',
+                  },
+              },
+          },
+      )
     return types.FunctionDeclaration(
         name=self.name,
         description=self.description,
diff --git a/tests/unittests/tools/retrieval/test_base_retrieval_tool.py b/tests/unittests/tools/retrieval/test_base_retrieval_tool.py
new file mode 100644
index 0000000000..8c40f49265
--- /dev/null
+++ b/tests/unittests/tools/retrieval/test_base_retrieval_tool.py
@@ -0,0 +1,67 @@
+# Copyright 2025 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.
+
+from google.adk.features import FeatureName
+from google.adk.features._feature_registry import temporary_feature_override
+from google.adk.tools.retrieval.base_retrieval_tool import BaseRetrievalTool
+from google.genai import types
+
+
+class _TestRetrievalTool(BaseRetrievalTool):
+  """Concrete implementation of BaseRetrievalTool for testing."""
+
+  def __init__(self):
+    super().__init__(
+        name='test_retrieval',
+        description='A test retrieval tool.',
+    )
+
+  async def run_async(self, *, args, tool_context):
+    return {'result': 'test'}
+
+
+def test_get_declaration_with_json_schema_feature_disabled():
+  """Test that _get_declaration uses parameters when feature is disabled."""
+  tool = _TestRetrievalTool()
+
+  with temporary_feature_override(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL, False):
+    declaration = tool._get_declaration()
+
+  assert declaration.name == 'test_retrieval'
+  assert declaration.description == 'A test retrieval tool.'
+  assert declaration.parameters_json_schema is None
+  assert isinstance(declaration.parameters, types.Schema)
+  assert declaration.parameters.type == types.Type.OBJECT
+  assert 'query' in declaration.parameters.properties
+
+
+def test_get_declaration_with_json_schema_feature_enabled():
+  """Test that _get_declaration uses parameters_json_schema when feature is enabled."""
+  tool = _TestRetrievalTool()
+
+  with temporary_feature_override(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL, True):
+    declaration = tool._get_declaration()
+
+  assert declaration.name == 'test_retrieval'
+  assert declaration.description == 'A test retrieval tool.'
+  assert declaration.parameters is None
+  assert declaration.parameters_json_schema == {
+      'type': 'object',
+      'properties': {
+          'query': {
+              'type': 'string',
+              'description': 'The query to retrieve.',
+          },
+      },
+  }
diff --git a/tests/unittests/tools/test_load_artifacts_tool.py b/tests/unittests/tools/test_load_artifacts_tool.py
index 1ea50bb33c..6a420574f0 100644
--- a/tests/unittests/tools/test_load_artifacts_tool.py
+++ b/tests/unittests/tools/test_load_artifacts_tool.py
@@ -14,6 +14,8 @@
 
 import base64
 
+from google.adk.features import FeatureName
+from google.adk.features._feature_registry import temporary_feature_override
 from google.adk.models.llm_request import LlmRequest
 from google.adk.tools.load_artifacts_tool import _maybe_base64_to_bytes
 from google.adk.tools.load_artifacts_tool import load_artifacts_tool
@@ -160,3 +162,21 @@ def test_maybe_base64_to_bytes_returns_none_for_invalid():
   """Invalid base64 strings return None."""
   # Single character is invalid (base64 requires length % 4 == 0 after padding)
   assert _maybe_base64_to_bytes('x') is None
+
+
+def test_get_declaration_with_json_schema_feature_enabled():
+  """Test that _get_declaration uses parameters_json_schema when feature is enabled."""
+  with temporary_feature_override(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL, True):
+    declaration = load_artifacts_tool._get_declaration()
+
+  assert declaration.name == 'load_artifacts'
+  assert declaration.parameters is None
+  assert declaration.parameters_json_schema == {
+      'type': 'object',
+      'properties': {
+          'artifact_names': {
+              'type': 'array',
+              'items': {'type': 'string'},
+          },
+      },
+  }
diff --git a/tests/unittests/tools/test_load_memory_tool.py b/tests/unittests/tools/test_load_memory_tool.py
new file mode 100644
index 0000000000..a3affd3ed3
--- /dev/null
+++ b/tests/unittests/tools/test_load_memory_tool.py
@@ -0,0 +1,46 @@
+# Copyright 2025 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.
+
+from google.adk.features import FeatureName
+from google.adk.features._feature_registry import temporary_feature_override
+from google.adk.tools.load_memory_tool import load_memory_tool
+from google.genai import types
+
+
+def test_get_declaration_with_json_schema_feature_disabled():
+  """Test that _get_declaration uses parameters when feature is disabled."""
+  with temporary_feature_override(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL, False):
+    declaration = load_memory_tool._get_declaration()
+
+  assert declaration.name == 'load_memory'
+  assert declaration.parameters_json_schema is None
+  assert isinstance(declaration.parameters, types.Schema)
+  assert declaration.parameters.type == types.Type.OBJECT
+  assert 'query' in declaration.parameters.properties
+
+
+def test_get_declaration_with_json_schema_feature_enabled():
+  """Test that _get_declaration uses parameters_json_schema when feature is enabled."""
+  with temporary_feature_override(FeatureName.JSON_SCHEMA_FOR_FUNC_DECL, True):
+    declaration = load_memory_tool._get_declaration()
+
+  assert declaration.name == 'load_memory'
+  assert declaration.parameters is None
+  assert declaration.parameters_json_schema == {
+      'type': 'object',
+      'properties': {
+          'query': {'type': 'string'},
+      },
+      'required': ['query'],
+  }