An AI agent is a model plus a harness. The model generates tokens; the harness decides which tools to expose, how context is assembled, what permissions apply, and how failures are handled.
Common harnesses include coding agents such as Claude Code, Codex, Cursor, and Windsurf, plus frameworks such as LangGraph, CrewAI, OpenAI Agents SDK, and deepagents. Each is a different way to wrap a model with tools and control flow.
OpenLIT does not replace your harness. It instruments any harness through OpenTelemetry so you can observe, evaluate, and improve it: traces for LLM and tool calls, evals on real trajectories, guardrails at runtime, and prompt or rule changes without redeploying.