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.
npx skills add FortiumPartners/ensemble --skill building-langgraph-agentsgit clone --depth 1 https://github.com/FortiumPartners/ensembleWrote 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.
[](https://agentmods.dev/skills/fortiumpartners/ensemble/building-langgraph-agents)<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/building-langgraph-agents"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/building-langgraph-agents/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/building-langgraph-agents"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/building-langgraph-agents.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00050 | $0.02388 |
| Opus 5 | $0.00025 | $0.01194 |
| Sonnet 5 | $0.00010 | $0.00478 |
| Haiku 4.5 | $0.00005 | $0.00239 |
Grade A, and why
building-langgraph-agents 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.
LangGraph Development Skill
Quick Reference
LangGraph is LangChain's framework for building stateful, multi-actor applications with LLMs. It enables cyclic graphs, conditional branching, persistent state management, and human-in-the-loop workflows.
Key capabilities: StateGraph for workflow orchestration, checkpointers for persistence, prebuilt ReAct agents, streaming at multiple granularities, and LangGraph Platform for managed deployment.
Table of Contents
- When to Use
- Package Ecosystem
- Quick Start - Python
- Quick Start - TypeScript
- Core Concepts
- Prebuilt Components
- Common Patterns
- Quick Persistence Setup
- CLI Commands
- Error Quick Reference
- When to Use REFERENCE.md
- Agent Integration
- See Also
When to Use
This skill is loaded by backend-developer when:
langgraphinrequirements.txt,pyproject.toml, orsetup.py@langchain/langgraphinpackage.jsondependencies- Python imports:
from langgraph.graph import StateGraph - Environment variables
LANGSMITH_API_KEY,LANGGRAPH_API_URL, orLANGCHAIN_API_KEYpresent - User mentions "LangGraph", "StateGraph", "agent workflow", "cyclic agent", or "multi-agent graph"
Package Ecosystem
| Package | Description |
|---|---|
langgraph |
Core StateGraph, MessageGraph, prebuilt components |
langgraph-checkpoint-postgres |
PostgreSQL checkpointer for production |
langgraph-checkpoint-sqlite |
SQLite checkpointer with async support |
langgraph-sdk |
Python client for LangGraph Platform API |
@langchain/langgraph |
TypeScript/JavaScript implementation |
Compatibility: LangGraph 0.2.x requires langchain-core>=0.3.0.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago First seen · 372 lines · 50 tokens per session scan A 9b3dcd6acf93
building-langgraph-agents is a skill published in the GitHub repository FortiumPartners/ensemble (12 stars, last pushed today), licensed MIT. It adds 50 tokens to every session and 2,388 once invoked, about $0.0003 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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