diff --git a/temporalio/contrib/openai_agents/workflow.py b/temporalio/contrib/openai_agents/workflow.py
index f5cc7f762..50eba0b9e 100644
--- a/temporalio/contrib/openai_agents/workflow.py
+++ b/temporalio/contrib/openai_agents/workflow.py
@@ -1,18 +1,27 @@
 """Workflow-specific primitives for working with the OpenAI Agents SDK in a workflow context"""
 
+import functools
+import inspect
 import json
 from datetime import timedelta
-from typing import Any, Callable, Optional, Type
+from typing import Any, Callable, Optional, Type, Union, overload
 
 import nexusrpc
 from agents import (
+    Agent,
     RunContextWrapper,
     Tool,
 )
-from agents.function_schema import function_schema
+from agents.function_schema import DocstringStyle, function_schema
 from agents.tool import (
     FunctionTool,
+    ToolErrorFunction,
+    ToolFunction,
+    ToolParams,
+    default_tool_error_function,
+    function_tool,
 )
+from agents.util._types import MaybeAwaitable
 
 from temporalio import activity
 from temporalio import workflow as temporal_workflow
@@ -78,6 +87,25 @@ def activity_as_tool(
             "Bare function without tool and activity decorators is not supported",
             "invalid_tool",
         )
+    if ret.name is None:
+        raise ApplicationError(
+            "Input activity must have a name to be made into a tool",
+            "invalid_tool",
+        )
+    # If the provided callable has a first argument of `self`, partially apply it with the same metadata
+    # The actual instance will be picked up by the activity execution, the partially applied function will never actually be executed
+    params = list(inspect.signature(fn).parameters.keys())
+    if len(params) > 0 and params[0] == "self":
+        partial = functools.partial(fn, None)
+        setattr(partial, "__name__", fn.__name__)
+        partial.__annotations__ = getattr(fn, "__annotations__")
+        setattr(
+            partial,
+            "__temporal_activity_definition",
+            getattr(fn, "__temporal_activity_definition"),
+        )
+        partial.__doc__ = fn.__doc__
+        fn = partial
     schema = function_schema(fn)
 
     async def run_activity(ctx: RunContextWrapper[Any], input: str) -> Any:
@@ -94,9 +122,8 @@ async def run_activity(ctx: RunContextWrapper[Any], input: str) -> Any:
         # Add the context to the arguments if it takes that
         if schema.takes_context:
             args = [ctx] + args
-
         result = await temporal_workflow.execute_activity(
-            fn,
+            ret.name,  # type: ignore
             args=args,
             task_queue=task_queue,
             schedule_to_close_timeout=schedule_to_close_timeout,
diff --git a/tests/contrib/openai_agents/test_openai.py b/tests/contrib/openai_agents/test_openai.py
index fe8584afc..57dc5c252 100644
--- a/tests/contrib/openai_agents/test_openai.py
+++ b/tests/contrib/openai_agents/test_openai.py
@@ -195,6 +195,17 @@ async def get_weather_context(ctx: RunContextWrapper[str], city: str) -> Weather
     return Weather(city=city, temperature_range="14-20C", conditions=ctx.context)
 
 
+class ActivityWeatherService:
+    @activity.defn
+    async def get_weather_method(self, city: str) -> Weather:
+        """
+        Get the weather for a given city.
+        """
+        return Weather(
+            city=city, temperature_range="14-20C", conditions="Sunny with wind."
+        )
+
+
 @nexusrpc.service
 class WeatherService:
     get_weather_nexus_operation: nexusrpc.Operation[WeatherInput, Weather]
@@ -269,6 +280,20 @@ class TestWeatherModel(StaticTestModel):
             usage=Usage(),
             response_id=None,
         ),
+        ModelResponse(
+            output=[
+                ResponseFunctionToolCall(
+                    arguments='{"city":"Tokyo"}',
+                    call_id="call",
+                    name="get_weather_method",
+                    type="function_call",
+                    id="id",
+                    status="completed",
+                )
+            ],
+            usage=Usage(),
+            response_id=None,
+        ),
         ModelResponse(
             output=[
                 ResponseOutputMessage(
@@ -333,7 +358,7 @@ class TestNexusWeatherModel(StaticTestModel):
 class ToolsWorkflow:
     @workflow.run
     async def run(self, question: str) -> str:
-        agent = Agent(
+        agent: Agent = Agent(
             name="Tools Workflow",
             instructions="You are a helpful agent.",
             tools=[
@@ -349,8 +374,12 @@ async def run(self, question: str) -> str:
                 openai_agents.workflow.activity_as_tool(
                     get_weather_context, start_to_close_timeout=timedelta(seconds=10)
                 ),
+                openai_agents.workflow.activity_as_tool(
+                    ActivityWeatherService.get_weather_method,
+                    start_to_close_timeout=timedelta(seconds=10),
+                ),
             ],
-        )  # type: Agent
+        )
         result = await Runner.run(
             starting_agent=agent, input=question, context="Stormy"
         )
@@ -406,6 +435,7 @@ async def test_tool_workflow(client: Client, use_local_model: bool):
                 get_weather_object,
                 get_weather_country,
                 get_weather_context,
+                ActivityWeatherService().get_weather_method,
             ],
             interceptors=[OpenAIAgentsTracingInterceptor()],
         ) as worker:
@@ -426,7 +456,7 @@ async def test_tool_workflow(client: Client, use_local_model: bool):
                     if e.HasField("activity_task_completed_event_attributes"):
                         events.append(e)
 
-                assert len(events) == 9
+                assert len(events) == 11
                 assert (
                     "function_call"
                     in events[0]
@@ -476,11 +506,23 @@ async def test_tool_workflow(client: Client, use_local_model: bool):
                     .data.decode()
                 )
                 assert (
-                    "Test weather result"
+                    "function_call"
                     in events[8]
                     .activity_task_completed_event_attributes.result.payloads[0]
                     .data.decode()
                 )
+                assert (
+                    "Sunny with wind"
+                    in events[9]
+                    .activity_task_completed_event_attributes.result.payloads[0]
+                    .data.decode()
+                )
+                assert (
+                    "Test weather result"
+                    in events[10]
+                    .activity_task_completed_event_attributes.result.payloads[0]
+                    .data.decode()
+                )
 
 
 @pytest.mark.parametrize("use_local_model", [True, False])