Production prompting goes far beyond "be specific". Few-shot examples outperform written instructions. Chain-of-thought unlocks reasoning. Structured output eliminates format failures. Chaining breaks complex tasks into reliable steps. And none of it matters without systematic evaluation.
Course: Advanced.
This lesson covers 5 concepts: Few-Shot Prompting, Chain-of-Thought, Structured Output, Prompt Chaining, Measuring Prompt Quality.
Few-shot prompting includes 2–5 worked examples in the prompt before the real query. The model infers the task format from the pattern — no rules, just demonstration.
For classification, extraction, and formatting tasks, 3 good examples typically outperform 2 pages of written instructions — and are far easier to maintain.
Instead of explaining what you want in words, show it. Three (input, output) examples teach the model your exact format more precisely than any written description.
Zero-shot: "Classify the sentiment" → inconsistent format. Three-shot: three (text, label) examples → consistent, correctly formatted output on new inputs every time.
Appending "Let's think step by step" or showing worked reasoning examples forces the model to reason before answering. Intermediate steps condition subsequent tokens toward correct conclusions.
CoT is free. A few extra output tokens typically improve complex reasoning accuracy by 10–40% on benchmarks — the highest-ROI prompt technique for reasoning tasks.
When the model writes out its reasoning, each step constrains the next to be logically consistent — errors have less room to accumulate.
Without CoT: "24 muffins, give away 1/3, make 18 more → 42" (wrong). With CoT: "24×1/3=8 given, 24−8=16, 16+18=34" → 34 (correct). Same model, same weights.
Structured output enforces valid JSON matching your schema via constrained decoding. The API guarantees the exact structure you specify — no parsing failures, no missing fields, no format surprises.
Without structured output, production pipelines break on format variations. With it, downstream code reliably parses model output — eliminating an entire class of errors.
Instead of hoping the model formats correctly, you specify exactly what structure you need and the API enforces it. The model becomes a reliable data transformation function.
"Extract product name and price" with no schema → sometimes JSON, sometimes prose. With response_format JSON schema → always {name: string, price: number}. Zero format failures.
Prompt chaining breaks a complex task into sequential LLM calls, each focused on one thing. Each call's output feeds the next, building complex behaviour from simple, verifiable pieces.
Chaining enables intermediate validation, parallel execution of independent steps, and easy debugging of exactly where errors enter the pipeline.
Like an assembly line — each station does one thing well. The final result comes from many small reliable steps, not one enormous fragile operation.
Single prompt: "summarise, translate, and reformat this document" — hard to debug. Chain: summarise → translate → reformat. Each step verifiable, each step replaceable.
Production prompts require systematic evaluation. A prompt that works on 5 manual tests may fail 15% of the time at scale. Build an eval suite — test cases with expected outputs — and measure pass rate before shipping any change.
Without eval, prompt changes are blind. With eval, you iterate confidently — measure before and after every change, catch regressions before they reach users.
Prompts are code. Test them like code. A prompt you are not measuring is a prompt you do not understand.
Format correct 98%: near-reliable. Test cases 94%: 6 in 100 produce wrong answers — find and fix before shipping. Factual accuracy 87%: needs grounding improvement.