Lesson 2: Tools = Dict — AgentCraft

LLM tool calling is a dictionary lookup: tools[name](**args). Build function calling from scratch in Python and see what LangChain's @tool decorator hides.

Tools = Dict You've seen this in ChatGPT: you ask "what's the weather?" and it calls a weather tool. Or in Claude: you ask it to search the web and it runs a search. The LLM can't run code — but it can say *"call add with a=10, b=5"* — a structured request. Your code executes it. > Framework parallel: LangChain's @tool decorator, CrewAI's tool registration — they build this dict for you. Here you'll see what's inside.

Concepts covered

tools
function calling
JSON schema
dispatch

Framework comparison: LangChain's @tool, CrewAI's tool registration — it's tools[name](**args).