ReasoningOfficial fact
Lower reasoning effort one step at a time
Reasoning effort should be matched to task complexity rather than fixed at the highest setting.
Applies to: OpenAI
Testing: Controlled lab recipe
Do: Compare the current effort with one level lower on a representative evaluation set.
Measure: Track reasoning tokens, quality-pass rate, latency, and accepted-answer cost.
Watch: A lower setting is not a saving if it causes retries or misses important constraints.
OutputOfficial fact
Give every response an output ceiling
An output-token limit bounds the most expensive side of a runaway generation.
Applies to: OpenAI
Testing: Controlled lab recipe
Do: Set a task-appropriate maximum and ask for concise structure rather than an open-ended answer.
Measure: Compare output tokens, truncation rate, retries, and quality-pass rate.
Watch: A ceiling that truncates valid answers creates extra calls and can increase total cost.
Prompt designTest protocol
Remove duplicated instructions before shortening prose
Rules often appear in system text, examples, tool descriptions, and the user prompt at the same time.
Applies to: OpenAI
Testing: Guided protocol
Do: Map each requirement to one authoritative location, then remove only true duplicates in a paired test.
Measure: Compare input tokens and constraint-pass rate across at least three repeats per case.
Watch: Repetition can be useful when it fixes a measured failure; do not remove it on aesthetics alone.
Prompt designTest protocol
Ablate examples one at a time
Few-shot examples are recurring input cost, but some may be carrying most of the quality gain.
Applies to: OpenAI
Testing: Guided protocol
Do: Remove one example, rerun the same evaluation set, and keep it removed only when quality remains inside the declared margin.
Measure: Track input-token reduction and per-example quality failures.
Watch: Deleting every example at once hides which one was valuable and makes regressions hard to diagnose.
OutputOfficial fact
Stop at a known delimiter
A stop sequence can prevent trailing explanations or repeated sections after the useful payload is complete.
Applies to: Google Gemini
Testing: Guide only · no lab adapter
Do: Choose a delimiter that cannot occur inside valid content, instruct the model to end with it, and configure the provider stop-sequence parameter.
Measure: Compare output tokens and incomplete-output rate, including delimiter-collision and escaping tests.
Watch: Stop support differs by model, and structured outputs are safer for complex JSON or content that may contain the delimiter.
OutputOfficial fact
Use low verbosity for machine-consumed answers
GPT-5.6 supports a low text-verbosity setting for shorter responses without relying only on prompt wording.
Applies to: OpenAI
Testing: Controlled lab recipe
Do: Use low verbosity for extraction, classification, routing, and other outputs where elaboration has no product value.
Measure: Compare output tokens, completeness, and retry rate.
Watch: Low verbosity can remove useful explanation from customer-facing or high-stakes answers.
Prompt designOfficial fact
Demonstrate the target answer length
A compact example can teach the desired response length and structure more concretely than a vague request to be concise.
Applies to: Google Gemini
Testing: Guided protocol
Do: Add one short example that contains every required element and no optional commentary, then remove prose that the example makes redundant.
Measure: Compare median output tokens, required-element recall, and retry rate with and without the concise example.
Watch: The example adds input tokens on every uncached request, so keep it only when output or retry savings exceed that recurring cost.
OutputDerived math
Remove preambles and task restatements
Machine-consumed answers rarely need to repeat the request or announce that the model is about to answer it.
Applies to: OpenAI
Testing: Guided protocol
Do: Tell the candidate to begin with the answer, omit greetings and conclusions, and never restate the task unless clarification is required.
Measure: Track output tokens, first-useful-token position, completeness, and the rate of confusingly abrupt answers.
Watch: Customer-facing explanations may need context or tone; do not remove framing that users demonstrably rely on.
OutputTest protocol
Put required answer elements before optional detail
A response budget is safer when the must-have fields or conclusions appear before explanation that can be shortened or omitted.
Applies to: OpenAI
Testing: Guided protocol
Do: List the required answer elements in priority order and tell the candidate to add optional rationale only when budget remains.
Measure: Compare required-field recall, truncation failures, output tokens, and human preference on the same tasks.
Watch: Some reasoning-heavy tasks need explanation before a defensible conclusion; use the product acceptance rubric, not length alone.
Structured outputDerived math
Encode closed choices as compact labels
A fixed decision can usually be returned as a short enum, boolean, or identifier instead of a repeated prose description.
Applies to: OpenAI
Testing: Guided protocol
Do: Give each allowed decision a stable compact label, ask for exactly one label, and map it to user-facing text in application code.
Measure: Compare output tokens, invalid-label rate, decision accuracy, and any repair calls against the prose response.
Watch: Compact labels hide nuance; keep a separate explanation field when downstream users need the reasoning.
Prompt designTest protocol
Replace style boilerplate with one success criterion
Several overlapping style instructions can often become one observable definition of a successful answer.
Applies to: OpenAI
Testing: Guided protocol
Do: Replace generic adjectives such as clear, helpful, thorough, and professional with one testable sentence describing what the answer must let the reader do.
Measure: Compare input tokens, evaluator pass rate, clarification requests, and output length across a representative task set.
Watch: Do not collapse distinct safety, policy, or contractual requirements merely because their wording looks repetitive.
OutputTest protocol
State a concrete response budget
A measurable word, sentence, bullet, or field budget gives the model a clearer stopping target than an unqualified request for brevity.
Applies to: OpenAI
Testing: Guided protocol
Do: Choose the smallest task-appropriate budget—for example three bullets or six fields—and state both the limit and the content that must fit inside it.
Measure: Track output tokens, budget violations, missing requirements, truncation, and retries against the current prompt.
Watch: Prompt budgets are soft controls; pair them with a safe API output ceiling for worst-case spend and leave headroom for valid edge cases.