Repository: langchain
Issue: When running OpenAI Assistant with tools: AttributeError: 'RequiredActionFunctionToolCall' object has no attribute 'tool'
Labels: 🤖:bug,investigate

### Checked other resources

- [x] I added a very descriptive title to this issue.
- [x] I searched the LangChain documentation with the integrated search.
- [x] I used the GitHub search to find a similar question and didn't find it.
- [x] I am sure that this is a bug in LangChain rather than my code.
- [x] The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

### Example Code

When running an AgentExecutor with an assistant, some some return value is not handled by the agent code.

Here is the code of a Chat agent (runs) and an Assitant:
```python

from langchain.agents.openai_assistant import OpenAIAssistantRunnable
from langchain.agents import Tool
from langchain.tools import StructuredTool, Tool
from langchain.agents import AgentExecutor,create_openai_tools_agent
import os

def gnix(*args, **kwargs):
    return f"The gnix is xing.\nReceived args: {args};\nreceived kwargs: {kwargs}"

# from pydantic import BaseModel, Field
# class NoArgs(BaseModel):
#     pass

# def gnix_noargs(_: NoArgs) -> str:
#     return "The gnix is xing."

tool = Tool.from_function(
        func=gnix,
        name="get_gnix",
        description="get the gnix. This function recieves no input and returns the gnix value.",
        # callbacks=[]
    )

tools = [tool]

message = "what tools do you have? can you get me the gnix?"
api_key = os.getenv("OPENAI_API_KEY")



from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder

prompt = ChatPromptTemplate.from_messages(
    [
        ("system", "You are a helpful assistant"),
        MessagesPlaceholder("chat_history", optional=True),
        ("human", "{input}"),
        MessagesPlaceholder("agent_scratchpad"),
    ]
)

model = ChatOpenAI()

agent = create_openai_tools_agent(model, tools, prompt)
agent_executor = AgentExecutor(agent=agent, tools=tools)

output = agent_executor.invoke({"input": "how is the gnix?"})

print(output["output"])



assistant = OpenAIAssistantRunnable.create_assistant( name="tmp",model="gpt-3.5-turbo", 
                        instructions="You are a helpful helper that can use tools.", tools=tools)



agent_executor = AgentExecutor(agent=assistant, tools=tools)
output = agent_executor.invoke({"content": message})
print(output["output"])
```

### Error Message and Stack Trace (if applicable)

python assistant_test.py

**The Chat output**

The gnix is xing! 

**The assistant output**

Traceback (most recent call last):
  File "/Users/danielnebenzahl/code/tmp/langchain/assistant_test.py", line 61, in <module>
    output = agent_executor.invoke({"content": message})
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/chains/base.py", line 170, in invoke
    raise e
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/chains/base.py", line 160, in invoke
    self._call(inputs, run_manager=run_manager)
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/agents/agent.py", line 1624, in _call
    next_step_output = self._take_next_step(
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/agents/agent.py", line 1330, in _take_next_step
    [
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/agents/agent.py", line 1330, in <listcomp>
    [
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/agents/agent.py", line 1415, in _iter_next_step
    yield self._perform_agent_action(
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/langchain/agents/agent.py", line 1429, in _perform_agent_action
    if agent_action.tool in name_to_tool_map:
  File "/Users/danielnebenzahl/.pyenv/versions/langchain/lib/python3.10/site-packages/pydantic/main.py", line 891, in __getattr__
    raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}')
AttributeError: 'RequiredActionFunctionToolCall' object has no attribute 'tool'

### Description

I expect AgentExecutor to work with assistants that use tools.

### System Info

python -m langchain_core.sys_info

System Information
------------------
> OS:  Darwin
> OS Version:  Darwin Kernel Version 23.6.0: Thu Sep 12 23:35:29 PDT 2024; root:xnu-10063.141.1.701.1~1/RELEASE_ARM64_T6000
> Python Version:  3.10.10 (main, May 16 2023, 17:41:32) [Clang 14.0.3 (clang-1403.0.22.14.1)]

Package Information
-------------------
> langchain_core: 0.3.29
> langchain: 0.3.14
> langsmith: 0.2.10
> langchain_openai: 0.3.0
> langchain_text_splitters: 0.3.5

Optional packages not installed
-------------------------------
> langserve

Other Dependencies
------------------
> aiohttp: 3.11.11
> async-timeout: 4.0.3
> httpx: 0.28.1
> jsonpatch: 1.33
> langsmith-pyo3: Installed. No version info available.
> numpy: 1.26.4
> openai: 1.59.7
> orjson: 3.10.14
> packaging: 24.2
> pydantic: 2.10.5
> PyYAML: 6.0.2
> requests: 2.32.3
> requests-toolbelt: 1.0.0
> SQLAlchemy: 2.0.37
> tenacity: 9.0.0
> tiktoken: 0.8.0
> typing-extensions: 4.12.2
> zstandard: Installed. No version info available.