About LangChainGuide

LangChain agents, retrieval and token cost

What this site covers

LangChainGuide covers building LLM applications with LangChain: how a chain or agent is actually executed, how retrieval is wired into it, and where the token budget goes once it is running.

• Agent orchestration and execution graphs
• Retrievers and vector-backed memory
• Prompt templates and structured output
• Tool calling and error handling
• Token cost and latency optimisation

8 articles are published so far. New ones are announced on the RSS feed.

Start here

The guides are written to be read in this order, each one assuming the previous.

1. LangChain building blocks: what the framework abstracts, and when an agent loop is the wrong choice.
2. LangChain RAG pipeline setup: loading, chunking, embeddings, storage and retrieval, stage by stage.
3. LangChain vs LangGraph: agents, state and control flow: which orchestration layer a given workload actually needs.
4. LangChain agent errors: runaway loops, skipped tools, bad arguments and parse failures, by symptom.

Alongside them, the token and agent cost sizer estimates what a multi-step agent run costs once step count, prompt size and retrieved context are known. It runs entirely in the browser and stores nothing.

How these articles are produced

Articles here are researched from primary sources: vendor and project documentation, published standards and specifications, research papers and preprints, and measurements published by whoever took them. Drafts are produced with AI assistance and then edited against those cited sources before anything is published.

No article on this site is based on first-hand testing in a private lab, and nothing here should be read as a measurement report of its own. Where a number appears, it comes from a source that is named, so you can check the original instead of taking this site's word for it.

Everything is published under a single editorial byline. That byline is a publishing identity for the site, not a claim about a named individual, and it does not carry professional credentials.

Corrections

Corrections are welcome. If something here is wrong, out of date, or attributed to the wrong source, email editor@langchainguide.com with the page address and what it should say. Substantive corrections are made in the article itself rather than quietly dropped.

How this site is funded

This site currently runs no affiliate links, sponsored posts, display advertising or paid placements. If that changes, the disclosure page will say so.

Contact

Email: editor@langchainguide.com
Site: langchainguide.com
Published by: LangChainGuide Editorial

See also the privacy policy, the terms of use, and the editorial disclosure.