openai: `bind_tools` not callable after `with_structured_output` · langchain-ai/langchain#28848

(15 comments) (4 reactions) (1 assignee)Python (136,758 stars) (22,617 forks)batch import

externalhelp wantedinvestigateopenai

Description

Checked other resources

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

Example Code

from langchain_openai import ChatOpenAI
from pydantic import BaseModel, Field
from langchain.tools import StructuredTool

class ResponseModel(BaseModel):
  a_value:str = Field(description="This doesn't matter much")

def a_func(val: int):
    return True

a_tool = StructuredTool.from_function(
            func=a_func,
            name="A func",
            description="A function you will need",
        )

llm = ChatOpenAI(model="gpt-4o-mini",temperature=0)
structured_llm = llm.with_structured_output(ResponseModel)
llm_with_tools = structured_llm.bind_tools([a_tool]) <----- not available

Error Message and Stack Trace (if applicable)

'RunnableSequence' object has no attribute 'bind_tools'

Description

I am attempting to retrieved structured output in a json format (to pass via an api to a frontend), and I also require calling out to tools. I cannot figure out how to combine the two, or there is an issue with code to do so.

System Info

System Information

OS: Darwin OS Version: Darwin Kernel Version 24.1.0: Thu Oct 10 21:02:27 PDT 2024; root:xnu-11215.41.3~2/RELEASE_X86_64 Python Version: 3.13.1 (main, Dec 3 2024, 17:59:52) [Clang 16.0.0 (clang-1600.0.26.4)]

Package Information

langchain_core: 0.3.28 langchain: 0.3.13 langchain_community: 0.3.13 langsmith: 0.2.4 langchain_experimental: 0.3.4 langchain_openai: 0.2.14 langchain_text_splitters: 0.3.4

Optional packages not installed

langserve

Other Dependencies

aiohttp: 3.10.10 async-timeout: Installed. No version info available. dataclasses-json: 0.6.7 httpx: 0.27.2 httpx-sse: 0.4.0 jsonpatch: 1.33 langsmith-pyo3: Installed. No version info available. numpy: 1.26.4 openai: 1.58.1 orjson: 3.10.9 packaging: 24.1 pydantic: 2.9.2 pydantic-settings: 2.6.0 PyYAML: 6.0.2 requests: 2.32.3 requests-toolbelt: 1.0.0 SQLAlchemy: 2.0.36 tenacity: 9.0.0 tiktoken: 0.8.0 typing-extensions: 4.12.2

Contributor guide

Tech stack: python
Domain: api
Issue type: bug
Difficulty: 3
Estimated time: half day
Activity status: blocked
Clarity: clear
Prerequisites: Python basicsLangChain APIPydantic basics
Newbie friendliness: 35
Research direction: Investigate the implementation of `with structured output` in `langchain openai` to understand why it returns a `RunnableSequence` that lacks `bind tools`. Check the comments in this issue for proposed workarounds and maintainer feedback. Look at the source code for `RunnableSequence` in `langchain core` to see if `bind tools` can be added or if there is an alternative approach to combine structured output and tool calling.