Normalize tool docstrings for schema conversion

[mindbomber]

Fixes #14

Summary

• Normalize the bundled tool function docstrings to Google-style Args: and Returns: indentation.
• Keep function behavior unchanged while making argument descriptions easier for LangChain's convert_to_openai_tool parser to preserve in generated tool schemas.

Verification

• AST docstring checker for @tool functions -> passed
• python -m py_compile functions.py -> passed
• git diff --check -> passed
• AANA code-change guardrail -> pass / accept, AIx 1.0, no violations

Note: full dependency installation is blocked in this local Python 3.13 environment because the repo pins torch==2.1.2 and pandas==2.2.0, which do not provide compatible wheels here.