langchain-agents (JavaScript/TypeScript)

Overview

Agents combine language models with tools to create systems that can reason about tasks, decide which tools to use, and iteratively work towards solutions. The createAgent() function provides a production-ready agent implementation built on LangGraph.

Key Concepts:

• Agent Loop: The model decides → calls tools → observes results → repeats until done
• ReAct Pattern: Reasoning and Acting - the agent reasons about what to do, then acts by calling tools
• Graph-based Runtime: Agents run on a LangGraph graph with nodes (model, tools, middleware) and edges

When to Use Agents