Building applications with LLMs through composability
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ccurme dcb5aba999
openai[patch]: reduce tested constraints on strict schema adherence for Responses API (#31290)
Scheduled testing started failing today because the Responses API
stopped raising `BadRequestError` for a schema that was previously
invalid when `strict=True`.

Although docs still say that [some type-specific keywords are not yet
supported](https://platform.openai.com/docs/guides/structured-outputs#some-type-specific-keywords-are-not-yet-supported)
(including `minimum` and `maximum` for numbers), the below appears to
run and correctly respect the constraints:
```python
import json
import openai

maximums = list(range(1, 11))
arg_values = []
for maximum in maximums:

    tool = {
        "type": "function",
        "name": "magic_function",
        "description": "Applies a magic function to an input.",
        "parameters": {
            "properties": {
                "input": {"maximum": maximum, "minimum": 0, "type": "integer"}
            },
            "required": ["input"],
            "type": "object",
            "additionalProperties": False
        },
        "strict": True
    }
    
    client = openai.OpenAI()
    
    response = client.responses.create(
        model="gpt-4.1",
        input=[{"role": "user", "content": "What is the value of magic_function(3)? Use the tool."}],
        tools=[tool],
    )
    function_call = next(item for item in response.output if item.type == "function_call")
    args = json.loads(function_call.arguments)
    arg_values.append(args["input"])


print(maximums)
print(arg_values)

# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
# [1, 2, 3, 3, 3, 3, 3, 3, 3, 3]
```
Until yesterday this raised BadRequestError.

The same is not true of Chat Completions, which appears to still raise
BadRequestError
```python
tool = {
    "type": "function",
    "function": {
        "name": "magic_function",
        "description": "Applies a magic function to an input.",
        "parameters": {
            "properties": {
                "input": {"maximum": 5, "minimum": 0, "type": "integer"}
            },
            "required": ["input"],
            "type": "object",
            "additionalProperties": False
        },
        "strict": True
    }
}

response = client.chat.completions.create(
    model="gpt-4.1",
    messages=[{"role": "user", "content": "What is the value of magic_function(3)? Use the tool."}],
    tools=[tool],
)
response  # raises BadRequestError
```

Here we update tests accordingly.
2025-05-20 14:50:31 +00:00
.devcontainer community[minor]: Add ApertureDB as a vectorstore (#24088) 2024-07-16 09:32:59 -07:00
.github voyageai: remove from monorepo (#31281) 2025-05-19 16:33:38 +00:00
cookbook docs: replace initialize_agent with create_react_agent in agent_vectorstore.ipynb (#31183) 2025-05-11 11:19:18 -04:00
docs Docs: Fixing a typo in retrievers concepts page (#31288) 2025-05-20 09:08:33 -04:00
libs openai[patch]: reduce tested constraints on strict schema adherence for Responses API (#31290) 2025-05-20 14:50:31 +00:00
scripts infra: update mypy 1.10, ruff 0.5 (#23721) 2024-07-03 10:33:27 -07:00
.gitattributes
.gitignore [performance]: Adding benchmarks for common langchain-core imports (#30747) 2025-04-09 13:00:15 -04:00
.pre-commit-config.yaml voyageai: remove from monorepo (#31281) 2025-05-19 16:33:38 +00:00
.readthedocs.yaml docs(readthedocs): streamline config (#30307) 2025-03-18 11:47:45 -04:00
CITATION.cff
LICENSE
Makefile infra: Suppress error in make api_docs_clean if index.md is missing (#31129) 2025-05-11 17:26:49 -04:00
MIGRATE.md Proofreading and Editing Report for Migration Guide (#28084) 2024-11-13 11:03:09 -05:00
poetry.toml multiple: use modern installer in poetry (#23998) 2024-07-08 18:50:48 -07:00
pyproject.toml community: move to separate repo (#31060) 2025-04-29 09:22:04 -04:00
README.md [performance]: Adding benchmarks for common langchain-core imports (#30747) 2025-04-09 13:00:15 -04:00
SECURITY.md docs: single security doc (#28515) 2024-12-04 18:15:34 +00:00
uv.lock core: Add ruff rules RUF (#29353) 2025-05-15 15:43:57 -04:00
yarn.lock box: add langchain box package and DocumentLoader (#25506) 2024-08-21 02:23:43 +00:00

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Note

Looking for the JS/TS library? Check out LangChain.js.

LangChain is a framework for building LLM-powered applications. It helps you chain together interoperable components and third-party integrations to simplify AI application development — all while future-proofing decisions as the underlying technology evolves.

pip install -U langchain

To learn more about LangChain, check out the docs. If youre looking for more advanced customization or agent orchestration, check out LangGraph, our framework for building controllable agent workflows.

Why use LangChain?

LangChain helps developers build applications powered by LLMs through a standard interface for models, embeddings, vector stores, and more.

Use LangChain for:

  • Real-time data augmentation. Easily connect LLMs to diverse data sources and external / internal systems, drawing from LangChains vast library of integrations with model providers, tools, vector stores, retrievers, and more.
  • Model interoperability. Swap models in and out as your engineering team experiments to find the best choice for your applications needs. As the industry frontier evolves, adapt quickly — LangChains abstractions keep you moving without losing momentum.

LangChains ecosystem

While the LangChain framework can be used standalone, it also integrates seamlessly with any LangChain product, giving developers a full suite of tools when building LLM applications.

To improve your LLM application development, pair LangChain with:

  • LangSmith - Helpful for agent evals and observability. Debug poor-performing LLM app runs, evaluate agent trajectories, gain visibility in production, and improve performance over time.
  • LangGraph - Build agents that can reliably handle complex tasks with LangGraph, our low-level agent orchestration framework. LangGraph offers customizable architecture, long-term memory, and human-in-the-loop workflows — and is trusted in production by companies like LinkedIn, Uber, Klarna, and GitLab.
  • LangGraph Platform - Deploy and scale agents effortlessly with a purpose-built deployment platform for long running, stateful workflows. Discover, reuse, configure, and share agents across teams — and iterate quickly with visual prototyping in LangGraph Studio.

Additional resources

  • Tutorials: Simple walkthroughs with guided examples on getting started with LangChain.
  • How-to Guides: Quick, actionable code snippets for topics such as tool calling, RAG use cases, and more.
  • Conceptual Guides: Explanations of key concepts behind the LangChain framework.
  • API Reference: Detailed reference on navigating base packages and integrations for LangChain.