diff --git a/rigging/__init__.py b/rigging/__init__.py
index 03ff1fa..7324336 100644
--- a/rigging/__init__.py
+++ b/rigging/__init__.py
@@ -14,6 +14,7 @@
     MapCompletionCallback,
     ThenCompletionCallback,
 )
+from rigging.error import Stop
 from rigging.generator import (
     GeneratedMessage,
     GeneratedText,
@@ -64,6 +65,7 @@
     "PipelineStepContextManager",
     "PipelineStepGenerator",
     "Prompt",
+    "Stop",
     "ThenChatCallback",
     "ThenCompletionCallback",
     "Tool",
diff --git a/rigging/chat.py b/rigging/chat.py
index 1ab091b..25008a6 100644
--- a/rigging/chat.py
+++ b/rigging/chat.py
@@ -720,7 +720,7 @@ def __init__(
         self.tool_mode: ToolMode = "auto"
         self.api_tool_choice: ApiToolChoice | None = None
         self.inject_tool_prompt = True
-        self.stop_on_tool_calls = True
+        self.add_tool_stop_token = True
         self.then_callbacks: list[tuple[ThenChatCallback, int]] = []
         self.map_callbacks: list[tuple[MapChatCallback, int]] = []
         self.watch_callbacks: list[WatchChatCallback] = watch_callbacks or []
@@ -880,6 +880,7 @@ def clone(
         *,
         only_messages: bool = False,
         chat: Chat | None = None,
+        callbacks: bool | t.Sequence[MapChatCallback | ThenChatCallback] = True,
     ) -> "ChatPipeline":
         """
         Creates a clone of the current `ChatPipeline` instance.
@@ -890,6 +891,8 @@ def clone(
                 including until callbacks, types, tools, metadata, etc.
             chat: An optional chat object clone for use in the new pipeline, otherwise the current
                 internal chat object will be cloned.
+            callbacks: If True (default), all callbacks will be cloned. If False, no callbacks will be cloned.
+                Otherwise provide a sequence of callbacks which should be maintained in the new pipeline.
 
         Returns:
             The cloned ChatPipeline.
@@ -906,16 +909,20 @@ def clone(
             new.tools = self.tools.copy()
             new.tool_mode = self.tool_mode
             new.metadata = deepcopy(self.metadata)
-            new.map_callbacks = self.map_callbacks.copy()
             new.on_failed = self.on_failed
             new.errors_to_catch = self.errors_to_catch.copy()
             new.errors_to_exclude = self.errors_to_exclude.copy()
             new.caching = self.caching
 
+            new.watch_callbacks = self.watch_callbacks.copy()
+
             # Check if any of our callbacks are bound methods to a ChatPipline.
             # If so, we should rebind them to `self` to ensure they work correctly
             # and aren't operating with old state.
 
+            if callbacks is False:
+                return new
+
             new.then_callbacks = [
                 (callback, max_depth)
                 if not hasattr(callback, "__self__")
@@ -931,6 +938,18 @@ def clone(
                 for callback, max_depth in self.map_callbacks.copy()
             ]
 
+            if not isinstance(callbacks, bool):
+                new.then_callbacks = [
+                    (callback, max_depth)
+                    for callback, max_depth in self.then_callbacks
+                    if callback in callbacks
+                ]
+                new.map_callbacks = [
+                    (callback, max_depth)
+                    for callback, max_depth in self.map_callbacks
+                    if callback in callbacks
+                ]
+
         return new
 
     def meta(self, **kwargs: t.Any) -> "ChatPipeline":
@@ -1105,7 +1124,7 @@ def using(
         mode: ToolMode | None = None,
         choice: ApiToolChoice | None = None,
         max_depth: int = DEFAULT_MAX_DEPTH,
-        stop_on_tool_calls: bool | None = None,
+        add_stop_token: bool | None = None,
     ) -> "ChatPipeline":
         """
         Adds a tool or a sequence of tools to participate in the generation process.
@@ -1119,7 +1138,8 @@ def using(
             mode: The tool calling mode to use (e.g., "xml", "json-in-xml", "api").
             choice: The API tool choice to use. This is only relevant when using the "api" tool mode.
             max_depth: The maximum depth for recursive tool calls (this is shared between all tools).
-            stop_on_tool_calls: When using natively parsed tools, whether to stop generation when a tool call block is observed.
+            add_stop_token: When using natively parsed tools ("xml", "json-in-xml"), use stop tokens to
+                immediately process a tool call when observed.
 
         Returns:
             The updated pipeline.
@@ -1172,8 +1192,8 @@ async def get_weather(city: Annotated[str, "The city name to get weather for"])
         if choice is not None:
             self.api_tool_choice = choice
 
-        if stop_on_tool_calls is not None:
-            self.stop_on_tool_calls = stop_on_tool_calls
+        if add_stop_token is not None:
+            self.add_tool_stop_token = add_stop_token
 
         return self
 
@@ -1237,7 +1257,7 @@ def until_parsed_as(
 
     async def _then_tools(self, chat: Chat) -> PipelineStepContextManager | None:
         if (
-            self.stop_on_tool_calls
+            self.add_tool_stop_token
             and self.tool_mode in ["xml", "json-in-xml"]
             and chat.stop_reason == "stop"
         ):
@@ -1270,31 +1290,26 @@ async def _then_tools(self, chat: Chat) -> PipelineStepContextManager | None:
         if not tool_calls:
             return None
 
-        next_pipeline = self.clone(chat=chat)
+        next_pipeline = self.clone(chat=chat, callbacks=[self._then_tools])
 
-        should_continue = True
+        stop = False
 
         for tool_call in tool_calls:
             tool = next((t for t in self.tools if t.name == tool_call.name), None)
             if tool is None:
                 raise UnknownToolError(tool_call.name)
 
-            message, _should_continue = await tool.handle_tool_call(tool_call)
+            message, _stop = await tool.handle_tool_call(tool_call)
+            stop = _stop if not _stop else stop
             next_pipeline.add(message)
 
-            # If the tool returns none, we should resolve tool calls, but
-            # not continue the pipeline.
-
-            if not _should_continue:
-                should_continue = _should_continue
-
         # Need to prevent infinite loops and treat tool_choice like
         # an ephemeral setting which resets after the first tool call.
 
         if self.tool_mode == "api" and next_pipeline.params:
             next_pipeline.params.tool_choice = None
 
-        if not should_continue:
+        if stop:
             # TODO(nick): Type hints here stop us from mixing step generators
             # and basic chat returns.
             return next_pipeline.chat  # type: ignore [return-value]
@@ -1302,7 +1317,7 @@ async def _then_tools(self, chat: Chat) -> PipelineStepContextManager | None:
         return next_pipeline.step()
 
     async def _then_parse(self, chat: Chat) -> PipelineStepContextManager | None:
-        next_pipeline = self.clone(chat=chat)
+        next_pipeline = self.clone(chat=chat, callbacks=[self._then_parse])
 
         try:
             chat.last.parse_many(*self.until_types)
@@ -1310,14 +1325,14 @@ async def _then_parse(self, chat: Chat) -> PipelineStepContextManager | None:
             next_pipeline.add(
                 Message.from_model(
                     ValidationErrorModel(content=str(e)),
-                    suffix="Rewrite your entire message with all the required xml structure.",
+                    suffix="Rewrite your entire message with all of the required xml elements.",
                 ),
             )
         except Exception as e:  # noqa: BLE001
             next_pipeline.add(
                 Message.from_model(
                     SystemErrorModel(content=str(e)),
-                    suffix="Rewrite your entire message with all the required xml structure.",
+                    suffix="Rewrite your entire message with all of the required xml elements.",
                 ),
             )
         else:  # parsed successfully
@@ -1336,7 +1351,7 @@ async def _pre_run(self) -> None:
                 self.chat.inject_tool_prompt(self.tools, self.tool_mode)
                 self.inject_native_tool_prompt = False
 
-            if self.stop_on_tool_calls:
+            if self.add_tool_stop_token:
                 self.params = self.params = GenerateParams()
                 self.params.stop = self.params.stop or []
                 self.params.stop.append(f"</{TOOL_CALLS_TAG}>")
diff --git a/rigging/error.py b/rigging/error.py
index cc0f5b5..1dc1acf 100644
--- a/rigging/error.py
+++ b/rigging/error.py
@@ -14,6 +14,38 @@
     from rigging.message import Message
 
 
+# User Throwable Exceptions
+
+
+class Stop(Exception):  # noqa: N818
+    """
+    Raise inside a pipeline to indicate a stopping condition.
+
+    Example:
+        ```
+        import rigging as rg
+
+        async def read_file(path: str) -> str:
+            "Read the contents of a file."
+
+            if no_more_files(path):
+                raise rg.Stop("There are no more files to read.")
+
+            ...
+
+        chat = await pipeline.using(read_file).run()
+        ```
+    """
+
+    def __init__(self, message: str):
+        super().__init__(message)
+        self.message = message
+        """The message associated with the stop."""
+
+
+# System Exceptions
+
+
 class UnknownToolError(Exception):
     """
     Raised when the an api tool call is made for an unknown tool.
diff --git a/rigging/prompt.py b/rigging/prompt.py
index 4ad7727..3a6431b 100644
--- a/rigging/prompt.py
+++ b/rigging/prompt.py
@@ -566,14 +566,14 @@ async def _then_parse(self, chat: Chat) -> PipelineStepContextManager | None:
             next_pipeline.add(
                 Message.from_model(
                     ValidationErrorModel(content=str(e)),
-                    suffix="Rewrite your entire message with all the required xml structure.",
+                    suffix="Rewrite your entire message with all of the required xml elements.",
                 ),
             )
         except Exception as e:  # noqa: BLE001
             next_pipeline.add(
                 Message.from_model(
                     SystemErrorModel(content=str(e)),
-                    suffix="Rewrite your entire message with all the required xml structure.",
+                    suffix="Rewrite your entire message with all of the required xml elements.",
                 ),
             )
         else:  # parsed successfully
@@ -1084,8 +1084,7 @@ def prompt(
     generator_id: str | None = None,
     tools: list[Tool[..., t.Any] | t.Callable[..., t.Any]] | None = None,
     system_prompt: str | None = None,
-) -> t.Callable[[t.Callable[P, t.Coroutine[t.Any, t.Any, R]] | t.Callable[P, R]], Prompt[P, R]]:
-    ...
+) -> t.Callable[[t.Callable[P, t.Coroutine[t.Any, t.Any, R]] | t.Callable[P, R]], Prompt[P, R]]: ...
 
 
 @t.overload
@@ -1098,8 +1097,7 @@ def prompt(
     generator_id: str | None = None,
     tools: list[Tool[..., t.Any] | t.Callable[..., t.Any]] | None = None,
     system_prompt: str | None = None,
-) -> Prompt[P, R]:
-    ...
+) -> Prompt[P, R]: ...
 
 
 @t.overload
@@ -1112,8 +1110,7 @@ def prompt(
     generator_id: str | None = None,
     tools: list[Tool[..., t.Any] | t.Callable[..., t.Any]] | None = None,
     system_prompt: str | None = None,
-) -> Prompt[P, R]:
-    ...
+) -> Prompt[P, R]: ...
 
 
 def prompt(
@@ -1214,8 +1211,12 @@ def make_prompt(
 
 
 @t.overload
-def make_prompt(content: str, return_type: type[R], *, ctx: Ctx | None = None) -> Prompt[..., R]:
-    ...
+def make_prompt(
+    content: str,
+    return_type: type[R],
+    *,
+    ctx: Ctx | None = None,
+) -> Prompt[..., R]: ...
 
 
 @t.overload
@@ -1224,8 +1225,7 @@ def make_prompt(
     return_type: None = None,
     *,
     ctx: Ctx | None = None,
-) -> Prompt[..., str]:
-    ...
+) -> Prompt[..., str]: ...
 
 
 def make_prompt(
diff --git a/rigging/tool/base.py b/rigging/tool/base.py
index 55e4844..c868d87 100644
--- a/rigging/tool/base.py
+++ b/rigging/tool/base.py
@@ -14,7 +14,7 @@
 import typing_extensions as te
 from pydantic import TypeAdapter
 
-from rigging.error import ToolDefinitionError
+from rigging.error import Stop, ToolDefinitionError
 from rigging.model import Model, make_from_schema, make_from_signature
 from rigging.tool.api import ApiFunctionDefinition, ApiToolCall, ApiToolDefinition
 from rigging.tool.native import (
@@ -258,7 +258,7 @@ def json_definition(self) -> JsonInXmlToolDefinition:
             parameters=json.dumps(self.parameters_schema),
         )
 
-    async def handle_tool_call(  # noqa: PLR0912
+    async def handle_tool_call(  # noqa: PLR0912, PLR0915
         self,
         tool_call: ApiToolCall | XmlToolCall | JsonInXmlToolCall,
     ) -> tuple["Message", bool]:
@@ -269,7 +269,8 @@ async def handle_tool_call(  # noqa: PLR0912
             tool_call: The tool call to handle.
 
         Returns:
-            The message to send back to the generator or `None` if iterative tool calling should not proceed any further.
+            A tuple containing the message to send back to the generator and a
+            boolean indicating whether tool calling should stop.
         """
 
         from rigging.message import ContentText, ContentTypes, Message
@@ -330,10 +331,16 @@ async def handle_tool_call(  # noqa: PLR0912
 
             # Call the function
 
+            stop = False
+
             try:
                 result: t.Any = self.fn(**kwargs)  # type: ignore [call-arg]
                 if inspect.isawaitable(result):
                     result = await result
+            except Stop as e:
+                result = f"<rg:stop>{e.message}</rg:stop>"
+                span.set_attribute("stop", True)
+                stop = True
             except Exception as e:
                 if self.catch is True or (
                     not isinstance(self.catch, bool) and isinstance(e, tuple(self.catch))
@@ -350,11 +357,6 @@ async def handle_tool_call(  # noqa: PLR0912
             else Message("user")
         )
 
-        # If the tool returns nothing back to us, we'll assume that
-        # they do not want to proceed with additional tool calling
-
-        should_continue = result is not None
-
         # If the tool gave us back anything that looks like a message, we'll
         # just pass it along. Otherwise we need to box up the result.
 
@@ -395,7 +397,7 @@ async def handle_tool_call(  # noqa: PLR0912
                 result=message.content_parts[0].text,
             ).to_pretty_xml()
 
-        return message, should_continue
+        return message, stop
 
     def __call__(self, *args: P.args, **kwargs: P.kwargs) -> R:
         return self.fn(*args, **kwargs)
diff --git a/tests/test_tool.py b/tests/test_tool.py
index 7919893..2563016 100644
--- a/tests/test_tool.py
+++ b/tests/test_tool.py
@@ -223,9 +223,9 @@ async def test_handle_api_tool_call(self, sample_tool: Tool[..., t.Any]) -> None
             ),
         )
 
-        message, should_continue = await sample_tool.handle_tool_call(tool_call)
+        message, stop = await sample_tool.handle_tool_call(tool_call)
 
-        assert should_continue is True
+        assert stop is False
         assert message is not None
         assert message.role == "tool"
         assert message.tool_call_id == "call123"
@@ -245,9 +245,9 @@ async def test_handle_xml_tool_call(self, sample_tool: Tool[..., t.Any]) -> None
             ).strip(),
         )
 
-        message, should_continue = await sample_tool.handle_tool_call(tool_call)
+        message, stop = await sample_tool.handle_tool_call(tool_call)
 
-        assert should_continue is True
+        assert stop is False
         assert message is not None
         assert message.role == "user"
         assert message.content == '<tool-result name="calculator">8</tool-result>'
@@ -260,9 +260,9 @@ async def test_handle_json_xml_tool_call(self, sample_tool: Tool[..., t.Any]) ->
             parameters=json.dumps({"a": 4, "b": 4, "operation": "add"}),
         )
 
-        message, should_continue = await sample_tool.handle_tool_call(tool_call)
+        message, stop = await sample_tool.handle_tool_call(tool_call)
 
-        assert should_continue is True
+        assert stop is False
         assert message is not None
         assert message.role == "user"
         assert message.content == '<tool-result name="calculator">8</tool-result>'
@@ -378,7 +378,7 @@ def faulty_function(x: int) -> int:
 
     tool = Tool.from_callable(faulty_function, catch={ValueError})
 
-    message, should_continue = await tool.handle_tool_call(tool_call)
+    message, stop = await tool.handle_tool_call(tool_call)
 
-    assert should_continue is True
+    assert stop is False
     assert "This is a test error" in message.content