Earendil Co-founder Explains What an Agent Harness Is
solyarisoftware · x · 2026-08-20
Earendil co-founder Colin Daymond published a blog post defining the 'Agent Harness'—the infrastructure that turns a model into an agent. At its core, a harness provides four essential components:
- System Prompt: Defines the agent's role and behavior.
- Tools: Grants the agent the ability to call external APIs or perform actions.
- Agentic Loop: Controls the iterative process of reasoning, acting, and observing.
- Translation Layer: Abstracts model differences to allow unified usage across different LLMs.
The post elaborates on how to build and own your harness, offering clarity for developers working on agent architectures.
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