core: Add ruff rules D (docstring) (#29406)

This ensures that the code is properly documented:
https://docs.astral.sh/ruff/rules/#pydocstyle-d

Related to #21983

libs/core/langchain_core/outputs/__init__.py

@@ -1,4 +1,6 @@
-"""**Output** classes are used to represent the output of a language model call
+"""Output classes.
+
+**Output** classes are used to represent the output of a language model call
 and the output of a chat.
 
 The top container for information is the `LLMResult` object. `LLMResult` is used by

libs/core/langchain_core/outputs/chat_generation.py

@@ -1,3 +1,5 @@
+"""Chat generation output classes."""
+
 from __future__ import annotations
 
 from typing import TYPE_CHECKING, Literal, Union
@@ -71,15 +73,11 @@ class ChatGeneration(Generation):
             raise ValueError(msg) from e
         return self
 
-    @classmethod
-    def get_lc_namespace(cls) -> list[str]:
-        """Get the namespace of the langchain object."""
-        return ["langchain", "schema", "output"]
-
 
 class ChatGenerationChunk(ChatGeneration):
-    """ChatGeneration chunk, which can be concatenated with other
-    ChatGeneration chunks.
+    """ChatGeneration chunk.
+
+    ChatGeneration chunks can be concatenated with other ChatGeneration chunks.
     """
 
     message: BaseMessageChunk
@@ -88,14 +86,15 @@ class ChatGenerationChunk(ChatGeneration):
     type: Literal["ChatGenerationChunk"] = "ChatGenerationChunk"  # type: ignore[assignment]
     """Type is used exclusively for serialization purposes."""
 
-    @classmethod
-    def get_lc_namespace(cls) -> list[str]:
-        """Get the namespace of the langchain object."""
-        return ["langchain", "schema", "output"]
-
     def __add__(
         self, other: Union[ChatGenerationChunk, list[ChatGenerationChunk]]
     ) -> ChatGenerationChunk:
+        """Concatenate two ChatGenerationChunks.
+
+        Args:
+            other: The other ChatGenerationChunk or list of ChatGenerationChunks to
+                concatenate.
+        """
         if isinstance(other, ChatGenerationChunk):
             generation_info = merge_dicts(
                 self.generation_info or {},

libs/core/langchain_core/outputs/chat_result.py

@@ -1,3 +1,5 @@
+"""Chat result schema."""
+
 from typing import Optional
 
 from pydantic import BaseModel

libs/core/langchain_core/outputs/generation.py

@@ -1,3 +1,5 @@
+"""Generation output schema."""
+
 from __future__ import annotations
 
 from typing import Any, Literal, Optional
@@ -41,19 +43,18 @@ class Generation(Serializable):
 
     @classmethod
     def get_lc_namespace(cls) -> list[str]:
-        """Get the namespace of the langchain object."""
+        """Get the namespace of the langchain object.
+
+        Default namespace is ["langchain", "schema", "output"].
+        """
         return ["langchain", "schema", "output"]
 
 
 class GenerationChunk(Generation):
     """Generation chunk, which can be concatenated with other Generation chunks."""
 
-    @classmethod
-    def get_lc_namespace(cls) -> list[str]:
-        """Get the namespace of the langchain object."""
-        return ["langchain", "schema", "output"]
-
     def __add__(self, other: GenerationChunk) -> GenerationChunk:
+        """Concatenate two GenerationChunks."""
         if isinstance(other, GenerationChunk):
             generation_info = merge_dicts(
                 self.generation_info or {},

libs/core/langchain_core/outputs/llm_result.py

@@ -1,3 +1,5 @@
+"""LLMResult class."""
+
 from __future__ import annotations
 
 from copy import deepcopy

libs/core/langchain_core/outputs/run_info.py

@@ -1,3 +1,5 @@
+"""RunInfo class."""
+
 from __future__ import annotations
 
 from uuid import UUID