Skill-Based Sub-Agents with LangGraph4j and Spring AI

Combine Tools & Skill to create Agent Modern agentic systems usually expose two strong but separate abstractions: Tools , which give an LLM executable capabilities Skills , which package reusable instructions for a narrow task This article shows how to combine both ideas in LangGraph4j so that a skill is not just prompt text, but a fully operational sub-agent exposed as a tool . The result is a practical pattern for building modular multi-agent systems in Java with Spring AI and LangGraph4j