How Hermes implements an open source agent harness architecture
Blog post from Arize
Hermes, developed by NousResearch, is an advanced open-source agent harness that distinguishes itself by implementing a comprehensive architecture for managing long-running coding agents. It excels in session management by treating sessions as infrastructure, separating tool registration from tool exposure, and employing lineage-based context compression, which ensures efficient resource use across CLI, messaging, and scheduled executions. Hermes stands out by integrating a nine-part harness model that includes context management, tool management, session persistence, and a robust prompt assembly system, effectively addressing challenges in open, long-running agent systems. Its architecture supports a wide range of platforms and enables the management of complex workflows through features like a messaging gateway and a profile system, which isolates agents to operate independently. Despite its strengths, Hermes still requires enhancements in durable child-run control to achieve first-class orchestration, a potential area for future development that could elevate its capabilities to match leading orchestration layers such as OpenClaw.