fix: Properly deserialize complex tool arguments with Temporal (#2686)

Author: DouweM

pydantic_ai_slim/pydantic_ai/durable_exec/temporal/_function_toolset.py

@@ -51,7 +51,10 @@ async def call_tool_activity(params: _CallToolParams, deps: AgentDepsT) -> Any:
                     'Removing or renaming tools during an agent run is not supported with Temporal.'
                 ) from e
 
-            return await self.wrapped.call_tool(name, params.tool_args, ctx, tool)
+            # The tool args will already have been validated into their proper types in the `ToolManager`,
+            # but `execute_activity` would have turned them into simple Python types again, so we need to re-validate them.
+            args_dict = tool.args_validator.validate_python(params.tool_args)
+            return await self.wrapped.call_tool(name, args_dict, ctx, tool)
 
         # Set type hint explicitly so that Temporal can take care of serialization and deserialization
         call_tool_activity.__annotations__['deps'] = deps_type
@@ -85,7 +88,11 @@ async def call_tool(
         return await workflow.execute_activity(  # pyright: ignore[reportUnknownMemberType]
             activity=self.call_tool_activity,
             args=[
-                _CallToolParams(name=name, tool_args=tool_args, serialized_run_context=serialized_run_context),
+                _CallToolParams(
+                    name=name,
+                    tool_args=tool_args,
+                    serialized_run_context=serialized_run_context,
+                ),
                 ctx.deps,
             ],
             **tool_activity_config,

tests/test_temporal.py

@@ -207,8 +207,15 @@ async def get_country(ctx: RunContext[Deps]) -> str:
     return ctx.deps.country
 
 
-def get_weather(city: str) -> str:
-    return 'sunny'
+class WeatherArgs(BaseModel):
+    city: str
+
+
+def get_weather(args: WeatherArgs) -> str:
+    if args.city == 'Mexico City':
+        return 'sunny'
+    else:
+        return 'unknown'  # pragma: no cover
 
 
 @dataclass