# LangChain Deep Agents LangChain Deep Agents is an open-source "batteries-included" agent harness built on top of [[LangGraph]]. It provides a pre-configured, opinionated agent system for complex, long-horizon tasks. Ships as a [[Python]] SDK (`deepagents`) and a terminal-based coding agent CLI. MIT license, Python >= 3.11. ## The four pillars The core algorithm remains unchanged from simple agents (LLM in a loop calling tools). The sophistication comes from four architectural components: 1. **Detailed system prompt**: comprehensive instructions guiding tool usage with few-shot examples, inspired by [[Claude Code]]'s long system prompts 2. **Planning tool** (`write_todos`): a built-in todo list mechanism that functions as context engineering rather than genuine task management. Breaks down complex tasks, tracks progress, adapts plans 3. **Sub-agents** (via `task` tool): spawns specialized child agents for subtasks with isolated context windows. Supports routing simpler tasks to cheaper models for cost optimization. Customizable via AGENTS.md files 4. **File system access**: persistent workspace allowing agents to store notes, maintain state, and collaborate. Pluggable backends (in-memory, local disk, LangGraph store, sandboxes like Modal/Daytona/Deno) ## Key insight The distinction between shallow and deep agents is not algorithmic. It is **context engineering**: carefully designed prompts, structured planning, task decomposition, and state persistence working together. ## CLI features Built-in tools for file operations, shell execution, HTTP requests, web search, sub-agent delegation, and context management. Supports persistent memory as markdown files, automatic context compaction, session resumption, and a skills system. Human-in-the-loop approval for sensitive operations. ## Provider agnostic Works with any LLM supporting tool calling (OpenAI, Anthropic, Google, [[Ollama]], Groq, xAI). Built on [[LangGraph]] for streaming, persistence, checkpointing, and production-ready runtime. ## References - https://docs.langchain.com/oss/python/deepagents/overview - https://blog.langchain.dev/deep-agents/ - https://github.com/langchain-ai/deepagents ## Related - [[LangChain]] - [[LangGraph]] - [[AI Agents]] - [[AI Agent Harness]] - [[AI Agent Orchestration]] - [[Claude Code]] - [[Agentic Engineering]] - [[Python]]