Glossary · Agents & tools
Agent Harness
The runtime around a model that assembles context, exposes tools, manages state, enforces limits, records traces, and decides when the agent should continue, retry, ask, or stop.
Why it matters
Two systems using the same model can perform very differently because their harnesses provide different context, tools, feedback, and safety boundaries.
In practice
Your harness can limit an agent to five tool calls, persist a checkpoint after each accepted patch, and require a passing test command before completion.
Common confusion
A harness is broader than a prompt template and narrower than the complete product.
Related terms
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