Hugging Face Publishes Definitive Agent Glossary — Harness vs. Scaffold vs. Agent Finally Defined

Hugging Face Blog·medium signal

Sergio Paniego and Aritra Roy Gosthipaty published a practical glossary on May 25 addressing the terminology confusion that peaked at ICLR 2026: Model (LLM, no memory, no loop), Scaffold (behavior-defining layer: system prompt, tool descriptions, context management), Harness (execution layer: calls model, handles tools, decides stopping), Agent (Model + Scaffold + Harness in an environment loop). The piece also formally defines context engineering, skills vs. tools, and sub-agents — terms the field has been using inconsistently across frameworks.