Hello World, LangChain

A first LangChain chain, from prompt template to LCEL pipe, with a local model swap, response inspection, tests, type-checking, and tracing added around it.

Agent Loops in Python

What actually happens between an LLM call and a tool call: the read-act-observe loop that turns a plain language model into an agent.

Tool Calling with LangChain

How create_agent and the @tool decorator collapse a hand-rolled tool-calling loop into a few lines, and what that trade-off actually costs you.

Structured Output as a Guardrail

How binding a Pydantic schema to a model or agent turns a probably-shaped response into a validated object, and what still isn’t guaranteed once it is.