_get_annotation_description() — langchain Function Reference

Architecture documentation for the _get_annotation_description() function in base.py from the langchain codebase.

Function python LangChainCore LanguageModelBase calls 1 called by 1

Entity Profile

LangChainCore→ LanguageModelBase→ _get_annotation_description() — langchain Function Reference

Dependency Diagram

graph TD
  644477c8_2315_71b4_87b9_459bd6db6814["_get_annotation_description()"]
  6508e071_ac7c_8516_5d11_f42f8a45558c["base.py"]
  644477c8_2315_71b4_87b9_459bd6db6814 -->|defined in| 6508e071_ac7c_8516_5d11_f42f8a45558c
  daa5e145_cf07_31db_8626_86e163af6615["_infer_arg_descriptions()"]
  daa5e145_cf07_31db_8626_86e163af6615 -->|calls| 644477c8_2315_71b4_87b9_459bd6db6814
  b5571bd9_2c1c_0fa8_e749_a69f0b3f4b64["_is_annotated_type()"]
  644477c8_2315_71b4_87b9_459bd6db6814 -->|calls| b5571bd9_2c1c_0fa8_e749_a69f0b3f4b64
  style 644477c8_2315_71b4_87b9_459bd6db6814 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/tools/base.py lines 105–123

def _get_annotation_description(arg_type: type) -> str | None:
    """Extract description from an `Annotated` type.

    Checks for string annotations and `FieldInfo` objects with descriptions.

    Args:
        arg_type: The type to extract description from.

    Returns:
        The description string if found, `None` otherwise.
    """
    if _is_annotated_type(arg_type):
        annotated_args = get_args(arg_type)
        for annotation in annotated_args[1:]:
            if isinstance(annotation, str):
                return annotation
            if isinstance(annotation, FieldInfo) and annotation.description:
                return annotation.description
    return None