Same question. Same model. Run two ways. On the left: nothing but the raw model. On the right: that exact model wrapped in a few rules - a harness. The gap between the two columns is what a harness actually buys you.
“Give me a recipe for chocolate cake”
No harness
Just the model. No instructions, no limits on length or topic.
Sure! Chocolate Cake Recipe: 2 cups flour, 2 cups sugar, 3/4 cup cocoa powder, 2 eggs, 1 cup milk, 1/2 cup oil, 2 tsp vanilla, 2 tsp baking powder... Preheat oven to 350°F. Mix dry ingredients, then wet. Combine. Bake 30–35 min. Let cool before frosting. Enjoy your cake!
Pre-written example - not a live model response
With a harness
Same model - given a system prompt and a length cap before it answers.
I only cover AI product-building here - things like harnesses, system prompts, and model selection. Try asking me something like "what is a harness?" instead.
Pre-written example - not a live model response
“Write a 10-paragraph essay on the history of Rome”
No harness
Just the model. No instructions, no limits on length or topic.
The Roman Empire began... (continues for ten full paragraphs, covering the founding myth, the Republic, the Punic Wars, Julius Caesar, the Empire's expansion, its eventual decline, and more - nothing stops it from writing the entire assignment.)
Pre-written example - not a live model response
With a harness
Same model - given a system prompt and a length cap before it answers.
That's outside what I cover here - I only answer questions about building AI products. Ask me about system prompts, turn limits, or model selection instead.
Pre-written example - not a live model response
“What is a harness, in plain terms?”
No harness
Just the model. No instructions, no limits on length or topic.
A harness, broadly speaking, can refer to several things depending on context. In animal care, it's a device... In technology, particularly in testing, a "test harness" refers to... In aviation and safety equipment... (keeps going, covering every meaning of the word at length).
Pre-written example - not a live model response
With a harness
Same model - given a system prompt and a length cap before it answers.
It's the code wrapped around an AI model that decides what it can talk about, how long a conversation runs, and what happens at the edges. The model stays the same - the harness is what makes it behave like a product instead of a toy.
Pre-written example - not a live model response