diff --git a/packages/toolbox-core/integration.cloudbuild.yaml b/packages/toolbox-core/integration.cloudbuild.yaml
index 61fd6afd..89132be9 100644
--- a/packages/toolbox-core/integration.cloudbuild.yaml
+++ b/packages/toolbox-core/integration.cloudbuild.yaml
@@ -43,4 +43,4 @@ options:
   logging: CLOUD_LOGGING_ONLY
 substitutions:
   _VERSION: '3.13'
-  _TOOLBOX_VERSION: '0.7.0'
+  _TOOLBOX_VERSION: '0.8.0'
diff --git a/packages/toolbox-core/src/toolbox_core/protocol.py b/packages/toolbox-core/src/toolbox_core/protocol.py
index e2071ba2..6606ef93 100644
--- a/packages/toolbox-core/src/toolbox_core/protocol.py
+++ b/packages/toolbox-core/src/toolbox_core/protocol.py
@@ -25,31 +25,39 @@ class ParameterSchema(BaseModel):
 
     name: str
     type: str
+    required: bool = True
     description: str
     authSources: Optional[list[str]] = None
     items: Optional["ParameterSchema"] = None
 
     def __get_type(self) -> Type:
+        base_type: Type
         if self.type == "string":
-            return str
+            base_type = str
         elif self.type == "integer":
-            return int
+            base_type = int
         elif self.type == "float":
-            return float
+            base_type = float
         elif self.type == "boolean":
-            return bool
+            base_type = bool
         elif self.type == "array":
             if self.items is None:
                 raise Exception("Unexpected value: type is 'list' but items is None")
-            return list[self.items.__get_type()]  # type: ignore
+            base_type = list[self.items.__get_type()]  # type: ignore
+        else:
+            raise ValueError(f"Unsupported schema type: {self.type}")
 
-        raise ValueError(f"Unsupported schema type: {self.type}")
+        if not self.required:
+            return Optional[base_type]  # type: ignore
+
+        return base_type
 
     def to_param(self) -> Parameter:
         return Parameter(
             self.name,
             Parameter.POSITIONAL_OR_KEYWORD,
             annotation=self.__get_type(),
+            default=Parameter.empty if self.required else None,
         )
 
 
diff --git a/packages/toolbox-core/src/toolbox_core/tool.py b/packages/toolbox-core/src/toolbox_core/tool.py
index 48a31dab..d9ec2883 100644
--- a/packages/toolbox-core/src/toolbox_core/tool.py
+++ b/packages/toolbox-core/src/toolbox_core/tool.py
@@ -13,6 +13,8 @@
 # limitations under the License.
 
 import copy
+import itertools
+from collections import OrderedDict
 from inspect import Signature
 from types import MappingProxyType
 from typing import Any, Awaitable, Callable, Mapping, Optional, Sequence, Union
@@ -89,7 +91,13 @@ def __init__(
         self.__params = params
         self.__pydantic_model = params_to_pydantic_model(name, self.__params)
 
-        inspect_type_params = [param.to_param() for param in self.__params]
+        # Separate parameters into required (no default) and optional (with
+        # default) to prevent the "non-default argument follows default
+        # argument" error when creating the function signature.
+        required_params = (p for p in self.__params if p.required)
+        optional_params = (p for p in self.__params if not p.required)
+        ordered_params = itertools.chain(required_params, optional_params)
+        inspect_type_params = [param.to_param() for param in ordered_params]
 
         # the following properties are set to help anyone that might inspect it determine usage
         self.__name__ = name
@@ -268,7 +276,9 @@ async def __call__(self, *args: Any, **kwargs: Any) -> str:
 
         # validate inputs to this call using the signature
         all_args = self.__signature__.bind(*args, **kwargs)
-        all_args.apply_defaults()  # Include default values if not provided
+
+        # The payload will only contain arguments explicitly provided by the user.
+        # Optional arguments not provided by the user will not be in the payload.
         payload = all_args.arguments
 
         # Perform argument type validations using pydantic
@@ -278,6 +288,11 @@ async def __call__(self, *args: Any, **kwargs: Any) -> str:
         for param, value in self.__bound_parameters.items():
             payload[param] = await resolve_value(value)
 
+        # Remove None values to prevent server-side type errors. The Toolbox
+        # server requires specific types for each parameter and will raise an
+        # error if it receives a None value, which it cannot convert.
+        payload = OrderedDict({k: v for k, v in payload.items() if v is not None})
+
         # create headers for auth services
         headers = {}
         for client_header_name, client_header_val in self.__client_headers.items():
diff --git a/packages/toolbox-core/src/toolbox_core/utils.py b/packages/toolbox-core/src/toolbox_core/utils.py
index 615a23ec..08a87a45 100644
--- a/packages/toolbox-core/src/toolbox_core/utils.py
+++ b/packages/toolbox-core/src/toolbox_core/utils.py
@@ -38,9 +38,8 @@ def create_func_docstring(description: str, params: Sequence[ParameterSchema]) -
         return docstring
     docstring += "\n\nArgs:"
     for p in params:
-        docstring += (
-            f"\n    {p.name} ({p.to_param().annotation.__name__}): {p.description}"
-        )
+        annotation = p.to_param().annotation
+        docstring += f"\n    {p.name} ({getattr(annotation, '__name__', str(annotation))}): {p.description}"
     return docstring
 
 
@@ -111,11 +110,20 @@ def params_to_pydantic_model(
     """Converts the given parameters to a Pydantic BaseModel class."""
     field_definitions = {}
     for field in params:
+
+        # Determine the default value based on the 'required' flag.
+        # '...' (Ellipsis) signifies a required field in Pydantic.
+        # 'None' makes the field optional with a default value of None.
+        default_value = ... if field.required else None
+
         field_definitions[field.name] = cast(
             Any,
             (
                 field.to_param().annotation,
-                Field(description=field.description),
+                Field(
+                    description=field.description,
+                    default=default_value,
+                ),
             ),
         )
     return create_model(tool_name, **field_definitions)
diff --git a/packages/toolbox-core/tests/test_e2e.py b/packages/toolbox-core/tests/test_e2e.py
index 8920bc3b..52f0ba56 100644
--- a/packages/toolbox-core/tests/test_e2e.py
+++ b/packages/toolbox-core/tests/test_e2e.py
@@ -11,6 +11,10 @@
 # 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 inspect import Parameter, signature
+from typing import Optional
+
 import pytest
 import pytest_asyncio
 from pydantic import ValidationError
@@ -64,7 +68,7 @@ async def test_load_toolset_specific(
     async def test_load_toolset_default(self, toolbox: ToolboxClient):
         """Load the default toolset, i.e. all tools."""
         toolset = await toolbox.load_toolset()
-        assert len(toolset) == 5
+        assert len(toolset) == 6
         tool_names = {tool.__name__ for tool in toolset}
         expected_tools = [
             "get-row-by-content-auth",
@@ -72,6 +76,7 @@ async def test_load_toolset_default(self, toolbox: ToolboxClient):
             "get-row-by-id-auth",
             "get-row-by-id",
             "get-n-rows",
+            "search-rows",
         ]
         assert tool_names == set(expected_tools)
 
@@ -217,3 +222,160 @@ async def test_run_tool_param_auth_no_field(
             match="no field named row_data in claims",
         ):
             await tool()
+
+
+@pytest.mark.asyncio
+@pytest.mark.usefixtures("toolbox_server")
+class TestOptionalParams:
+    """
+    End-to-end tests for tools with optional parameters.
+    """
+
+    async def test_tool_signature_is_correct(self, toolbox: ToolboxClient):
+        """Verify the client correctly constructs the signature for a tool with optional params."""
+        tool = await toolbox.load_tool("search-rows")
+        sig = signature(tool)
+
+        assert "email" in sig.parameters
+        assert "data" in sig.parameters
+        assert "id" in sig.parameters
+
+        # The required parameter should have no default
+        assert sig.parameters["email"].default is Parameter.empty
+        assert sig.parameters["email"].annotation is str
+
+        # The optional parameter should have a default of None
+        assert sig.parameters["data"].default is None
+        assert sig.parameters["data"].annotation is Optional[str]
+
+        # The optional parameter should have a default of None
+        assert sig.parameters["id"].default is None
+        assert sig.parameters["id"].annotation is Optional[int]
+
+    async def test_run_tool_with_optional_params_omitted(self, toolbox: ToolboxClient):
+        """Invoke a tool providing only the required parameter."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com")
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" in response
+        assert "row3" not in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_optional_data_provided(self, toolbox: ToolboxClient):
+        """Invoke a tool providing both required and optional parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", data="row3")
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" not in response
+        assert "row3" in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_optional_data_null(self, toolbox: ToolboxClient):
+        """Invoke a tool providing both required and optional parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", data=None)
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" in response
+        assert "row3" not in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_optional_id_provided(self, toolbox: ToolboxClient):
+        """Invoke a tool providing both required and optional parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=1)
+        assert isinstance(response, str)
+        assert response == "null"
+
+    async def test_run_tool_with_optional_id_null(self, toolbox: ToolboxClient):
+        """Invoke a tool providing both required and optional parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=None)
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" in response
+        assert "row3" not in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_missing_required_param(self, toolbox: ToolboxClient):
+        """Invoke a tool without its required parameter."""
+        tool = await toolbox.load_tool("search-rows")
+        with pytest.raises(TypeError, match="missing a required argument: 'email'"):
+            await tool(id=5, data="row5")
+
+    async def test_run_tool_with_required_param_null(self, toolbox: ToolboxClient):
+        """Invoke a tool without its required parameter."""
+        tool = await toolbox.load_tool("search-rows")
+        with pytest.raises(ValidationError, match="email"):
+            await tool(email=None, id=5, data="row5")
+
+    async def test_run_tool_with_all_default_params(self, toolbox: ToolboxClient):
+        """Invoke a tool providing all parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=0, data="row2")
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" in response
+        assert "row3" not in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_all_valid_params(self, toolbox: ToolboxClient):
+        """Invoke a tool providing all parameters."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=3, data="row3")
+        assert isinstance(response, str)
+        assert '"email":"twishabansal@google.com"' in response
+        assert "row1" not in response
+        assert "row2" not in response
+        assert "row3" in response
+        assert "row4" not in response
+        assert "row5" not in response
+        assert "row6" not in response
+
+    async def test_run_tool_with_different_email(self, toolbox: ToolboxClient):
+        """Invoke a tool providing all parameters but with a different email."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="anubhavdhawan@google.com", id=3, data="row3")
+        assert isinstance(response, str)
+        assert response == "null"
+
+    async def test_run_tool_with_different_data(self, toolbox: ToolboxClient):
+        """Invoke a tool providing all parameters but with a different data."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=3, data="row4")
+        assert isinstance(response, str)
+        assert response == "null"
+
+    async def test_run_tool_with_different_id(self, toolbox: ToolboxClient):
+        """Invoke a tool providing all parameters but with a different data."""
+        tool = await toolbox.load_tool("search-rows")
+
+        response = await tool(email="twishabansal@google.com", id=4, data="row3")
+        assert isinstance(response, str)
+        assert response == "null"
diff --git a/packages/toolbox-core/tests/test_protocol.py b/packages/toolbox-core/tests/test_protocol.py
index a70fa3fe..b7650792 100644
--- a/packages/toolbox-core/tests/test_protocol.py
+++ b/packages/toolbox-core/tests/test_protocol.py
@@ -14,6 +14,7 @@
 
 
 from inspect import Parameter
+from typing import Optional
 
 import pytest
 
@@ -106,3 +107,66 @@ def test_parameter_schema_unsupported_type_error():
 
     with pytest.raises(ValueError, match=expected_error_msg):
         schema.to_param()
+
+
+def test_parameter_schema_string_optional():
+    """Tests an optional ParameterSchema with type 'string'."""
+    schema = ParameterSchema(
+        name="nickname",
+        type="string",
+        description="An optional nickname",
+        required=False,
+    )
+    expected_type = Optional[str]
+
+    # Test __get_type()
+    assert schema._ParameterSchema__get_type() == expected_type
+
+    # Test to_param()
+    param = schema.to_param()
+    assert isinstance(param, Parameter)
+    assert param.name == "nickname"
+    assert param.annotation == expected_type
+    assert param.kind == Parameter.POSITIONAL_OR_KEYWORD
+    assert param.default is None
+
+
+def test_parameter_schema_required_by_default():
+    """Tests that a parameter is required by default."""
+    # 'required' is not specified, so it should default to True.
+    schema = ParameterSchema(name="id", type="integer", description="A required ID")
+    expected_type = int
+
+    # Test __get_type()
+    assert schema._ParameterSchema__get_type() == expected_type
+
+    # Test to_param()
+    param = schema.to_param()
+    assert isinstance(param, Parameter)
+    assert param.name == "id"
+    assert param.annotation == expected_type
+    assert param.default == Parameter.empty
+
+
+def test_parameter_schema_array_optional():
+    """Tests an optional ParameterSchema with type 'array'."""
+    item_schema = ParameterSchema(name="", type="integer", description="")
+    schema = ParameterSchema(
+        name="optional_scores",
+        type="array",
+        description="An optional list of scores",
+        items=item_schema,
+        required=False,
+    )
+    expected_type = Optional[list[int]]
+
+    # Test __get_type()
+    assert schema._ParameterSchema__get_type() == expected_type
+
+    # Test to_param()
+    param = schema.to_param()
+    assert isinstance(param, Parameter)
+    assert param.name == "optional_scores"
+    assert param.annotation == expected_type
+    assert param.kind == Parameter.POSITIONAL_OR_KEYWORD
+    assert param.default is None
diff --git a/packages/toolbox-core/tests/test_utils.py b/packages/toolbox-core/tests/test_utils.py
index c07f44cb..b3ddd7c3 100644
--- a/packages/toolbox-core/tests/test_utils.py
+++ b/packages/toolbox-core/tests/test_utils.py
@@ -34,6 +34,7 @@ def create_param_mock(name: str, description: str, annotation: Type) -> Mock:
     param_mock = Mock(spec=ParameterSchema)
     param_mock.name = name
     param_mock.description = description
+    param_mock.required = True
 
     mock_param_info = Mock()
     mock_param_info.annotation = annotation
diff --git a/packages/toolbox-langchain/integration.cloudbuild.yaml b/packages/toolbox-langchain/integration.cloudbuild.yaml
index b5ae5510..0deb3a94 100644
--- a/packages/toolbox-langchain/integration.cloudbuild.yaml
+++ b/packages/toolbox-langchain/integration.cloudbuild.yaml
@@ -44,4 +44,4 @@ options:
   logging: CLOUD_LOGGING_ONLY
 substitutions:
   _VERSION: '3.13'
-  _TOOLBOX_VERSION: '0.7.0'
+  _TOOLBOX_VERSION: '0.8.0'
diff --git a/packages/toolbox-langchain/tests/test_e2e.py b/packages/toolbox-langchain/tests/test_e2e.py
index 12002717..64371ead 100644
--- a/packages/toolbox-langchain/tests/test_e2e.py
+++ b/packages/toolbox-langchain/tests/test_e2e.py
@@ -75,13 +75,14 @@ async def test_aload_toolset_specific(
 
     async def test_aload_toolset_all(self, toolbox):
         toolset = await toolbox.aload_toolset()
-        assert len(toolset) == 5
+        assert len(toolset) == 6
         tool_names = [
             "get-n-rows",
             "get-row-by-id",
             "get-row-by-id-auth",
             "get-row-by-email-auth",
             "get-row-by-content-auth",
+            "search-rows",
         ]
         for tool in toolset:
             name = tool._ToolboxTool__core_tool.__name__
@@ -220,13 +221,14 @@ def test_load_toolset_specific(
 
     def test_aload_toolset_all(self, toolbox):
         toolset = toolbox.load_toolset()
-        assert len(toolset) == 5
+        assert len(toolset) == 6
         tool_names = [
             "get-n-rows",
             "get-row-by-id",
             "get-row-by-id-auth",
             "get-row-by-email-auth",
             "get-row-by-content-auth",
+            "search-rows",
         ]
         for tool in toolset:
             name = tool._ToolboxTool__core_tool.__name__
diff --git a/packages/toolbox-llamaindex/integration.cloudbuild.yaml b/packages/toolbox-llamaindex/integration.cloudbuild.yaml
index 6e15f8a1..9b0b4e5d 100644
--- a/packages/toolbox-llamaindex/integration.cloudbuild.yaml
+++ b/packages/toolbox-llamaindex/integration.cloudbuild.yaml
@@ -44,4 +44,4 @@ options:
   logging: CLOUD_LOGGING_ONLY
 substitutions:
   _VERSION: '3.13'
-  _TOOLBOX_VERSION: '0.7.0'
+  _TOOLBOX_VERSION: '0.8.0'
diff --git a/packages/toolbox-llamaindex/tests/test_e2e.py b/packages/toolbox-llamaindex/tests/test_e2e.py
index 5f389b86..580059a7 100644
--- a/packages/toolbox-llamaindex/tests/test_e2e.py
+++ b/packages/toolbox-llamaindex/tests/test_e2e.py
@@ -75,13 +75,14 @@ async def test_aload_toolset_specific(
 
     async def test_aload_toolset_all(self, toolbox):
         toolset = await toolbox.aload_toolset()
-        assert len(toolset) == 5
+        assert len(toolset) == 6
         tool_names = [
             "get-n-rows",
             "get-row-by-id",
             "get-row-by-id-auth",
             "get-row-by-email-auth",
             "get-row-by-content-auth",
+            "search-rows",
         ]
         for tool in toolset:
             name = tool._ToolboxTool__core_tool.__name__
@@ -220,13 +221,14 @@ def test_load_toolset_specific(
 
     def test_aload_toolset_all(self, toolbox):
         toolset = toolbox.load_toolset()
-        assert len(toolset) == 5
+        assert len(toolset) == 6
         tool_names = [
             "get-n-rows",
             "get-row-by-id",
             "get-row-by-id-auth",
             "get-row-by-email-auth",
             "get-row-by-content-auth",
+            "search-rows",
         ]
         for tool in toolset:
             name = tool._ToolboxTool__core_tool.__name__