Learning track · 4 short lessons
Why the harness matters
The model is only one part of an agent. Its tools, environment, feedback loop, and limits determine what it can actually do—and how safely you can rely on it. This track starts with the system boundary and ends with a fair way to measure the whole setup.
Read in order · About 24 minutes · Each lesson includes an example and a quick check
Lessons
LESSON 01 · 5 min
Anatomy of an agent harness
Separate the model, harness, tools, and environment—and identify what each is responsible for.
LESSON 02 · 6 min
Close the feedback loop
Trace a tool request through validation, execution, observation, recovery, and the next model turn.
LESSON 03 · 6 min
Boundaries make autonomy usable
Apply least authority, action checks, budgets, and error policies to tool-enabled agents.
LESSON 04 · 7 min
Evaluate the whole harness
Design a fair evaluation that measures task success, process, latency, and cost for a fixed configuration.
Ready to build the pieces yourself? Continue to How to build →
Lessons draw on primary engineering and research sources. See the agent harness field guide for a printable checklist.