Standardize docstrings and improve coverage

[baskaryan]

Issue

Every public module, class, method and attribute should have a docstring.

Requirements

• All docstrings should follow the Google Python Style Guide.
• Examples should use RST code-block format so that they render in the API reference correctly.

NOTE!

RST code block must have a newline between .. code-block:: python and the code example, and code example must be tabbed, to render correctly!

Examples

Module

langchain/foo/__init__.py

""""One line summary.

More detailed paragraph.
"""

Class and attributes

Not Pydantic class

class Foo:
  """One line summary.

  More detailed paragraph.
  
  Attributes:
    first_attr: does first thing.
    second_attr: does second thing.

  Example:
    .. code-block:: python
    
      from langchain.foo import Foo
  
      f = Foo(1, 2, "bar")
      ...
  """
  
  def __init__(self, a: int, b: int, c: str) -> None:
    """Initialize using a, b, c.
   
    Args:
      a: ...
      b: ...
      c: ...
   """
    self.first_attr = a + b
    self.second_attr = c

NOTE

If the object attributes and init args are the same then you can just document the init args for non-Pydantic classes and just document the attributes for Pydantic classes.

Pydantic class

from typing import Any

from langchain_core.base_models import BaseModel

class FooPydantic(BaseModel):
  """One line summary.

  More detailed paragraph.

  Example:
    .. code-block:: python
    
      from langchain.foo import Foo
  
      f = Foo(1, 2, "bar")
      ...
  """

  first_attr: int
  """Does first thing."""
  second_attr: str
  """Does second thing.

  Additional info if needed.
  """

    def __init__(self, a: int, b: int, c: str, **kwargs: Any) -> None:
    """Initialize using a, b, c.
   
    Args:
      a: ...
      b: ...
      c: ...
      **kwargs: ...
   """
    first_attr = a + b
    second_attr = c
    super().__init__(first_attr=first_attr, second_attr=second_attr, **kwargs)

Function/method

def bar(a: int, b: str) -> float:
  """One line description.

  More description if needed.

  Args:
    a: ...
    b: ...

  Returns:
    A float of ...

  Raises:
    ValueError: If a is negative.

  Example:
    .. code-block:: python
      
      from langchain.foo import bar

      bar(1, "foo")
      # -> 14.381
  """

[klaudialemiec]

I will start!

[dosubot]

Hi, @baskaryan. I'm helping the LangChain team manage their backlog and am marking this issue as stale.

Your issue highlights the need for standardizing docstrings across all public modules, classes, methods, and attributes to align with the Google Python Style Guide. You mentioned specific formatting requirements for examples using RST code-block format, and @klaudialemiec has expressed their intention to begin addressing this.

Could you please let us know if this issue is still relevant to the latest version of the LangChain repository? If it is, feel free to comment here to keep it open. Otherwise, you can close it yourself, or it will be automatically closed in 7 days. Thank you!