im trying to understand the llama

are you talking about the llama tools? https://gpt-index.readthedocs.io/en/latest/how_to/integrations/using_with_langchain.html#llama-tool-abstractions

We provide tools that you can use with a langchain agent, as well as some utility functions to easily instantiate a langchain agent with llama tools from indexes/graphs:

take a look at this nb as well: https://github.com/jerryjliu/llama_index/blob/main/examples/chatbot/Chatbot_SEC.ipynb

create_llama_chat_agent just creates a langchain agent with llamaindex tools