Generate tool call id if not present

docs/agents.md

@@ -748,7 +748,7 @@ with capture_run_messages() as messages:  # (2)!
                     ToolCallPart(
                         tool_name='calc_volume',
                         args={'size': 6},
-                        tool_call_id=None,
+                        tool_call_id='pyd_ai_tool_call_id',
                         part_kind='tool-call',
                     )
                 ],
@@ -761,7 +761,7 @@ with capture_run_messages() as messages:  # (2)!
                     RetryPromptPart(
                         content='Please try again.',
                         tool_name='calc_volume',
-                        tool_call_id=None,
+                        tool_call_id='pyd_ai_tool_call_id',
                         timestamp=datetime.datetime(...),
                         part_kind='retry-prompt',
                     )
@@ -773,7 +773,7 @@ with capture_run_messages() as messages:  # (2)!
                     ToolCallPart(
                         tool_name='calc_volume',
                         args={'size': 6},
-                        tool_call_id=None,
+                        tool_call_id='pyd_ai_tool_call_id',
                         part_kind='tool-call',
                     )
                 ],

docs/testing-evals.md

@@ -93,7 +93,7 @@ Here's how we would write tests using [`TestModel`][pydantic_ai.models.test.Test
 from datetime import timezone
 import pytest
 
-from dirty_equals import IsNow
+from dirty_equals import IsNow, IsStr
 
 from pydantic_ai import models, capture_run_messages
 from pydantic_ai.models.test import TestModel
@@ -146,7 +146,7 @@ async def test_forecast():
                         'location': 'a',
                         'forecast_date': '2024-01-01',  # (8)!
                     },
-                    tool_call_id=None,
+                    tool_call_id=IsStr(),
                 )
             ],
             model_name='test',
@@ -157,7 +157,7 @@ async def test_forecast():
                 ToolReturnPart(
                     tool_name='weather_forecast',
                     content='Sunny with a chance of rain',
-                    tool_call_id=None,
+                    tool_call_id=IsStr(),
                     timestamp=IsNow(tz=timezone.utc),
                 ),
             ],

docs/tools.md

@@ -87,7 +87,10 @@ print(dice_result.all_messages())
     ModelResponse(
         parts=[
             ToolCallPart(
-                tool_name='roll_die', args={}, tool_call_id=None, part_kind='tool-call'
+                tool_name='roll_die',
+                args={},
+                tool_call_id='pyd_ai_tool_call_id',
+                part_kind='tool-call',
             )
         ],
         model_name='gemini-1.5-flash',
@@ -99,7 +102,7 @@ print(dice_result.all_messages())
             ToolReturnPart(
                 tool_name='roll_die',
                 content='4',
-                tool_call_id=None,
+                tool_call_id='pyd_ai_tool_call_id',
                 timestamp=datetime.datetime(...),
                 part_kind='tool-return',
             )
@@ -111,7 +114,7 @@ print(dice_result.all_messages())
             ToolCallPart(
                 tool_name='get_player_name',
                 args={},
-                tool_call_id=None,
+                tool_call_id='pyd_ai_tool_call_id',
                 part_kind='tool-call',
             )
         ],
@@ -124,7 +127,7 @@ print(dice_result.all_messages())
             ToolReturnPart(
                 tool_name='get_player_name',
                 content='Anne',
-                tool_call_id=None,
+                tool_call_id='pyd_ai_tool_call_id',
                 timestamp=datetime.datetime(...),
                 part_kind='tool-return',
             )

pydantic_ai_slim/pydantic_ai/_parts_manager.py

@@ -29,6 +29,8 @@
     ToolCallPartDelta,
 )
 
+from ._utils import generate_tool_call_id as _generate_tool_call_id
+
 VendorId = Hashable
 """
 Type alias for a vendor identifier, which can be any hashable type (e.g., a string, UUID, etc.)
@@ -221,7 +223,11 @@ def handle_tool_call_part(
             ModelResponseStreamEvent: A `PartStartEvent` indicating that a new tool call part
             has been added to the manager, or replaced an existing part.
         """
-        new_part = ToolCallPart(tool_name=tool_name, args=args, tool_call_id=tool_call_id)
+        new_part = ToolCallPart(
+            tool_name=tool_name,
+            args=args,
+            tool_call_id=tool_call_id or _generate_tool_call_id(),
+        )
         if vendor_part_id is None:
             # vendor_part_id is None, so we unconditionally append a new ToolCallPart to the end of the list
             new_part_index = len(self._parts)

pydantic_ai_slim/pydantic_ai/_utils.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import time
+import uuid
 from collections.abc import AsyncIterable, AsyncIterator, Iterator
 from contextlib import asynccontextmanager, suppress
 from dataclasses import dataclass, is_dataclass
@@ -195,12 +196,17 @@ def now_utc() -> datetime:
     return datetime.now(tz=timezone.utc)
 
 
-def guard_tool_call_id(
-    t: _messages.ToolCallPart | _messages.ToolReturnPart | _messages.RetryPromptPart, model_source: str
-) -> str:
-    """Type guard that checks a `tool_call_id` is not None both for static typing and runtime."""
-    assert t.tool_call_id is not None, f'{model_source} requires `tool_call_id` to be set: {t}'
-    return t.tool_call_id
+def guard_tool_call_id(t: _messages.ToolCallPart | _messages.ToolReturnPart | _messages.RetryPromptPart) -> str:
+    """Type guard that either returns the tool call id or generates a new one if it's None."""
+    return t.tool_call_id or generate_tool_call_id()
+
+
+def generate_tool_call_id() -> str:
+    """Generate a tool call id.
+
+    Ensure that the tool call id is unique.
+    """
+    return f'pyd_ai_{uuid.uuid4().hex}'
 
 
 class PeekableAsyncStream(Generic[T]):

pydantic_ai_slim/pydantic_ai/messages.py

@@ -12,7 +12,7 @@
 from opentelemetry._events import Event
 from typing_extensions import TypeAlias
 
-from ._utils import now_utc as _now_utc
+from ._utils import generate_tool_call_id as _generate_tool_call_id, now_utc as _now_utc
 from .exceptions import UnexpectedModelBehavior
 
 
@@ -268,8 +268,8 @@ class ToolReturnPart:
     content: Any
     """The return value."""
 
-    tool_call_id: str | None = None
-    """Optional tool call identifier, this is used by some models including OpenAI."""
+    tool_call_id: str
+    """The tool call identifier, this is used by some models including OpenAI."""
 
     timestamp: datetime = field(default_factory=_now_utc)
     """The timestamp, when the tool returned."""
@@ -328,8 +328,11 @@ class RetryPromptPart:
     tool_name: str | None = None
     """The name of the tool that was called, if any."""
 
-    tool_call_id: str | None = None
-    """Optional tool call identifier, this is used by some models including OpenAI."""
+    tool_call_id: str = field(default_factory=_generate_tool_call_id)
+    """The tool call identifier, this is used by some models including OpenAI.
+
+    In case the tool call id is not provided by the model, PydanticAI will generate a random one.
+    """
 
     timestamp: datetime = field(default_factory=_now_utc)
     """The timestamp, when the retry was triggered."""
@@ -406,8 +409,11 @@ class ToolCallPart:
     This is stored either as a JSON string or a Python dictionary depending on how data was received.
     """
 
-    tool_call_id: str | None = None
-    """Optional tool call identifier, this is used by some models including OpenAI."""
+    tool_call_id: str = field(default_factory=_generate_tool_call_id)
+    """The tool call identifier, this is used by some models including OpenAI.
+
+    In case the tool call id is not provided by the model, PydanticAI will generate a random one.
+    """
 
     part_kind: Literal['tool-call'] = 'tool-call'
     """Part type identifier, this is available on all parts as a discriminator."""
@@ -564,11 +570,7 @@ def as_part(self) -> ToolCallPart | None:
         if self.tool_name_delta is None or self.args_delta is None:
             return None
 
-        return ToolCallPart(
-            self.tool_name_delta,
-            self.args_delta,
-            self.tool_call_id,
-        )
+        return ToolCallPart(self.tool_name_delta, self.args_delta, self.tool_call_id or _generate_tool_call_id())
 
     @overload
     def apply(self, part: ModelResponsePart) -> ToolCallPart: ...
@@ -620,20 +622,11 @@ def _apply_to_delta(self, delta: ToolCallPartDelta) -> ToolCallPart | ToolCallPa
             delta = replace(delta, args_delta=updated_args_delta)
 
         if self.tool_call_id:
-            # Set the tool_call_id if it wasn't present, otherwise error if it has changed
-            if delta.tool_call_id is not None and delta.tool_call_id != self.tool_call_id:
-                raise UnexpectedModelBehavior(
-                    f'Cannot apply a new tool_call_id to a ToolCallPartDelta that already has one ({delta=}, {self=})'
-                )
             delta = replace(delta, tool_call_id=self.tool_call_id)
 
         # If we now have enough data to create a full ToolCallPart, do so
         if delta.tool_name_delta is not None and delta.args_delta is not None:
-            return ToolCallPart(
-                delta.tool_name_delta,
-                delta.args_delta,
-                delta.tool_call_id,
-            )
+            return ToolCallPart(delta.tool_name_delta, delta.args_delta, delta.tool_call_id or _generate_tool_call_id())
 
         return delta
 
@@ -656,11 +649,6 @@ def _apply_to_part(self, part: ToolCallPart) -> ToolCallPart:
             part = replace(part, args=updated_dict)
 
         if self.tool_call_id:
-            # Replace the tool_call_id entirely if given
-            if part.tool_call_id is not None and part.tool_call_id != self.tool_call_id:
-                raise UnexpectedModelBehavior(
-                    f'Cannot apply a new tool_call_id to a ToolCallPartDelta that already has one ({part=}, {self=})'
-                )
             part = replace(part, tool_call_id=self.tool_call_id)
         return part
 

pydantic_ai_slim/pydantic_ai/models/anthropic.py

@@ -326,7 +326,7 @@ async def _map_message(self, messages: list[ModelMessage]) -> tuple[str, list[Me
                             user_content_params.append(content)
                     elif isinstance(request_part, ToolReturnPart):
                         tool_result_block_param = ToolResultBlockParam(
-                            tool_use_id=_guard_tool_call_id(t=request_part, model_source='Anthropic'),
+                            tool_use_id=_guard_tool_call_id(t=request_part),
                             type='tool_result',
                             content=request_part.model_response_str(),
                             is_error=False,
@@ -337,7 +337,7 @@ async def _map_message(self, messages: list[ModelMessage]) -> tuple[str, list[Me
                             retry_param = TextBlockParam(type='text', text=request_part.model_response())
                         else:
                             retry_param = ToolResultBlockParam(
-                                tool_use_id=_guard_tool_call_id(t=request_part, model_source='Anthropic'),
+                                tool_use_id=_guard_tool_call_id(t=request_part),
                                 type='tool_result',
                                 content=request_part.model_response(),
                                 is_error=True,
@@ -351,7 +351,7 @@ async def _map_message(self, messages: list[ModelMessage]) -> tuple[str, list[Me
                         assistant_content_params.append(TextBlockParam(text=response_part.content, type='text'))
                     else:
                         tool_use_block_param = ToolUseBlockParam(
-                            id=_guard_tool_call_id(t=response_part, model_source='Anthropic'),
+                            id=_guard_tool_call_id(t=response_part),
                             type='tool_use',
                             name=response_part.tool_name,
                             input=response_part.args_as_dict(),

pydantic_ai_slim/pydantic_ai/models/bedrock.py

@@ -394,10 +394,9 @@ async def _map_user_prompt(part: UserPromptPart) -> list[MessageUnionTypeDef]:
 
     @staticmethod
     def _map_tool_call(t: ToolCallPart) -> ContentBlockOutputTypeDef:
-        assert t.tool_call_id is not None
         return {
             'toolUse': {
-                'toolUseId': t.tool_call_id,
+                'toolUseId': _utils.guard_tool_call_id(t=t),
                 'name': t.tool_name,
                 'input': t.args_as_dict(),
             }

pydantic_ai_slim/pydantic_ai/models/cohere.py

@@ -10,7 +10,7 @@
 from typing_extensions import assert_never, deprecated
 
 from .. import ModelHTTPError, result
-from .._utils import guard_tool_call_id as _guard_tool_call_id
+from .._utils import generate_tool_call_id as _generate_tool_call_id, guard_tool_call_id as _guard_tool_call_id
 from ..messages import (
     ModelMessage,
     ModelRequest,
@@ -225,7 +225,7 @@ def _process_response(self, response: ChatResponse) -> ModelResponse:
                     ToolCallPart(
                         tool_name=c.function.name,
                         args=c.function.arguments,
-                        tool_call_id=c.id,
+                        tool_call_id=c.id or _generate_tool_call_id(),
                     )
                 )
         return ModelResponse(parts=parts, model_name=self._model_name)
@@ -262,7 +262,7 @@ def _get_tools(self, model_request_parameters: ModelRequestParameters) -> list[T
     @staticmethod
     def _map_tool_call(t: ToolCallPart) -> ToolCallV2:
         return ToolCallV2(
-            id=_guard_tool_call_id(t=t, model_source='Cohere'),
+            id=_guard_tool_call_id(t=t),
             type='function',
             function=ToolCallV2Function(
                 name=t.tool_name,
@@ -294,7 +294,7 @@ def _map_user_message(cls, message: ModelRequest) -> Iterable[ChatMessageV2]:
             elif isinstance(part, ToolReturnPart):
                 yield ToolChatMessageV2(
                     role='tool',
-                    tool_call_id=_guard_tool_call_id(t=part, model_source='Cohere'),
+                    tool_call_id=_guard_tool_call_id(t=part),
                     content=part.model_response_str(),
                 )
             elif isinstance(part, RetryPromptPart):
@@ -303,7 +303,7 @@ def _map_user_message(cls, message: ModelRequest) -> Iterable[ChatMessageV2]:
                 else:
                     yield ToolChatMessageV2(
                         role='tool',
-                        tool_call_id=_guard_tool_call_id(t=part, model_source='Cohere'),
+                        tool_call_id=_guard_tool_call_id(t=part),
                         content=part.model_response(),
                     )
             else:

pydantic_ai_slim/pydantic_ai/models/gemini.py

@@ -263,7 +263,6 @@ async def _make_request(
             url = f'/{self._model_name}:{"streamGenerateContent" if streamed else "generateContent"}'
 
         request_json = _gemini_request_ta.dump_json(request_data, by_alias=True)
-
         async with self.client.stream(
             'POST',
             url,
@@ -603,12 +602,7 @@ def _process_response_from_parts(
         if 'text' in part:
             items.append(TextPart(content=part['text']))
         elif 'function_call' in part:
-            items.append(
-                ToolCallPart(
-                    tool_name=part['function_call']['name'],
-                    args=part['function_call']['args'],
-                )
-            )
+            items.append(ToolCallPart(tool_name=part['function_call']['name'], args=part['function_call']['args']))
         elif 'function_response' in part:
             raise UnexpectedModelBehavior(
                 f'Unsupported response from Gemini, expected all parts to be function calls or text, got: {part!r}'

pydantic_ai_slim/pydantic_ai/models/groq.py

@@ -309,7 +309,7 @@ def _map_message(self, message: ModelMessage) -> Iterable[chat.ChatCompletionMes
     @staticmethod
     def _map_tool_call(t: ToolCallPart) -> chat.ChatCompletionMessageToolCallParam:
         return chat.ChatCompletionMessageToolCallParam(
-            id=_guard_tool_call_id(t=t, model_source='Groq'),
+            id=_guard_tool_call_id(t=t),
             type='function',
             function={'name': t.tool_name, 'arguments': t.args_as_json_str()},
         )
@@ -335,7 +335,7 @@ def _map_user_message(cls, message: ModelRequest) -> Iterable[chat.ChatCompletio
             elif isinstance(part, ToolReturnPart):
                 yield chat.ChatCompletionToolMessageParam(
                     role='tool',
-                    tool_call_id=_guard_tool_call_id(t=part, model_source='Groq'),
+                    tool_call_id=_guard_tool_call_id(t=part),
                     content=part.model_response_str(),
                 )
             elif isinstance(part, RetryPromptPart):
@@ -344,7 +344,7 @@ def _map_user_message(cls, message: ModelRequest) -> Iterable[chat.ChatCompletio
                 else:
                     yield chat.ChatCompletionToolMessageParam(
                         role='tool',
-                        tool_call_id=_guard_tool_call_id(t=part, model_source='Groq'),
+                        tool_call_id=_guard_tool_call_id(t=part),
                         content=part.model_response(),
                     )