Bug Description

_parse_google_docstring in langchain_core/utils/function_calling.py incorrectly parses multi-line argument descriptions when a continuation line contains a colon. The continuation line is treated as a new argument definition instead of being appended to the current argument's description.

Reproduction

from langchain_core.utils.function_calling import _parse_google_docstring

def search(query: str, top_k: int = 5) -> str:
    """Search the knowledge base.

    Args:
        query: The search query to use
            for finding things: important ones
        top_k: Number of results to return
    """

result = _parse_google_docstring(search.__doc__, ["query", "top_k"])
print(result)

Expected: 2 args: query (description: "The search query to use for finding things: important ones"), top_k

Actual: 3 args: query, for finding things (treated as a new arg name), top_k

Root Cause

The parser uses if ":" in line to detect new argument lines without considering indentation. In Google-style docstrings, continuation lines have deeper indentation than argument definition lines, but the parser doesn't distinguish between them.

Proposed Fix

Detect the base indentation level from the first argument line and treat any line with deeper indentation as a continuation of the current argument's description, regardless of whether it contains a colon.