LangChain Fundamentals

LangChain Fundamentals is a skill for Claude Code, Codex from jackjin1997/ClawForge. It costs 27 tokens per session (3,110 once invoked), scanned A, original, no licence file.

A guide to building LangChain agents, which are programs that use language models to choose actions and call tools. It covers agent creation, tool definitions, and middleware for approvals and errors.

In plain words
What is it for?
Use it to create agents, define the tools they can use, add human approval, and manage errors.
Why use it?
It explains the basic pieces needed to build agents that can perform tasks with tools and handle interruptions or failures.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to create agents, define the tools they can use, add human approval, and manage errors.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jackjin1997/clawforge/langchain-fundamentals
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add jackjin1997/ClawForge --skill langchain-fundamentals
Clone the repo
git clone --depth 1 https://github.com/jackjin1997/ClawForge

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for LangChain Fundamentals

README.md
[![agentmods](https://agentmods.dev/badge/skills/jackjin1997/clawforge/langchain-fundamentals.svg)](https://agentmods.dev/skills/jackjin1997/clawforge/langchain-fundamentals)
Your own site
<a href="https://agentmods.dev/skills/jackjin1997/clawforge/langchain-fundamentals"><img src="https://agentmods.dev/badge/skills/jackjin1997/clawforge/langchain-fundamentals.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,110 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00027 $0.03110
Opus 5 $0.00014 $0.01555
Sonnet 5 $0.00005 $0.00622
Haiku 4.5 $0.00003 $0.00311

Measured 8d ago against content hash 964a208f5a22, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

LangChain Fundamentals scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/langchain-fundamentals/SKILL.md · 393 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 393 lines · 27 tokens per session scan A 964a208f5a22

Subscribe to this mod's changes

LangChain Fundamentals is a skill published in the GitHub repository jackjin1997/ClawForge (12 stars, last pushed 2mo ago), with no licence file. It adds 27 tokens to every session and 3,110 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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