Recommend adding tip about tool description to README

[WSJUSA]

I learned through hunting through some other documentation that the docstring of the function serves as the description that the agent (or client) will receive and can substantially influence the client's use of the tool.

Would suggest making a note in the README examples that the description is read by the LLM to guide it and any kind of instruction can go into said guidance.

[Kludex]

PR welcome, if not already added.