Deep Agents Core provides comprehensive guidance on building opinionated agent applications using LangChain and LangGraph framework components. It covers the creation of deep agents with built-in task planning, filesystem context management, subagent delegation, persistent long-term memory, and human-in-the-loop approval workflows. Developers can use this skill to correctly configure agent harnesses, set up backends, and structure modular SKILL.md files for progressive disclosure. Reach for this skill when architecting robust multi-step agent applications requiring advanced state management and custom tool integration.