Down-Skilling: Opus → Haiku Distillation

Translate your reasoning capabilities into explicit, structured instructions that Haiku 5.5 can execute reliably. You are a compiler: your input is context, intent, and domain knowledge; your output is a Haiku-ready prompt with decision procedures and diverse examples.

Core Principle

Opus infers from WHY. Haiku executes from WHAT and HOW.

Your job: convert implicit reasoning, contextual judgment, and domain expertise into explicit procedures, concrete decision trees, and demonstrative examples. Every inference you would make silently, Haiku needs stated explicitly.

Economics: Why Examples Are Free

Opus 5.5 costs 40× Haiku 5.5 on both sides ($4/$20 vs $0.10/$0.50 per MTok for prompts up to 100K tokens; 2026-10 pricing), and Sonnet 5.5 costs 20×. A task that costs $1.00 on Opus costs ~$0.025 on Haiku, so retries no longer erase the saving: Haiku can fail and retry a dozen times and still cost less than one Opus attempt. (At Haiku 4.5's $1/$5 it was 5×, and one retry halved the saving.) What a misfire costs now is mostly silent error, a plausible wrong answer no verifier caught, not dollars.

The math that matters:

• Input tokens are cheap (Haiku 5.5: $0.10/MTok input vs $0.50/MTok output)
• Adding 2,000 tokens of examples costs ~$0.0002 per call
• Give the orchestrator a verifier and an informed retry (the prior output plus

the check's failure output). On a 2026-10-07 repair battery, Haiku 5.5 rescued every rung-1 miss that way (agent-routing)

• What prevents the misfires a verifier cannot see is a test set run before shipping,

not a larger example block (see Start Bare below)

What this means for prompt design:

• If you're sending an 8K token document, you can afford 3-4K tokens of

examples — the examples cost less than the document itself

• Lengthy input prompts don't inflate output costs — output pricing is

independent of input length

• The constraint is not token cost but diminishing returns: after 5-7

examples, additional examples rarely improve performance

Bottom line: At 5.5 prices, tokens are no longer the constraint. The expensive mistakes are a judgment rule shipped without the example that calibrates it, and examples standing in for a test set. Both cost you a wrong answer that ships.

Haiku 5.5: Start Bare, Then Add Only What a Miss Asks For

Measured 2026-10-07 on three of this skill's own distilled prompts (feedback extraction, moderation, SQL), each run as shipped, with its <examples> stripped, and bare (task, label names and output schema only); two replicates (oaustegard/experiments → downskill-shots):

Three things follow. Haiku 5.5 does not need examples to apply a rule. Rules written for an example-heavy prompt mislead it once the examples are gone, because it reads them literally: "surface content hostile → flag" flagged a harsh opinion about an article, which the example had shown as APPROVED. And a house convention the model would not guess (spending counts completed orders only) transferred through its example in 1 of 2 runs, so state it as a rule.

Procedure on Haiku 5.5:

1. Write the bare prompt: role, task, every valid label, the output schema.
2. Write 10–20 test inputs with expected outputs, at least a third of them at

decision boundaries. Run the bare prompt on them.

1. For each miss, add the smallest thing that fixes it:

• an unstated default or house convention ("some" means LIMIT 10; spending

counts completed orders) → one explicit rule;

• a judgment boundary (opinion versus harassment, MIXED versus NEGATIVE) → one

example at that boundary, with its <reasoning>. Never a judgment rule without the example that calibrates it.

1. Rerun. Stop when the test set passes; typical-case examples add nothing here.
2. For rewriting and summarisation, keep an explicit no-invention rule: without

one, 3 of 8 rewrites stated facts the source does not ("We tested it across a range of workloads"). Don't count on a fact-listing step against invention. On 5.5, 0 of 64 rewrites invented a technical detail whether that step was hidden in the process, a visible <facts> block, a list supplied in the prompt, or absent (retested 2026-10-08). The anti-invention examples (model the silence) are optional too: the set that drove Haiku 4.5 to 19 of 20 produced 0 of 8 on 5.5.

1. A fact list decides what the rewrite carries over, so choose it on purpose:

• A list Haiku writes itself records the source's claims about itself as facts

("the team describes it as a paradigm shift"), and the rewrite repeats them (8/8). If those should go, say so as a rule.

• A list supplied in the prompt is followed omissions and all: a supplied list

that left out "it is launching" produced 2 of 8 rewrites calling the product "in beta". Supply one only when it has been checked against the source.

1. Don't instruct Haiku 5.5's reasoning ("think in 3-5 steps", "in your reasoning,

first list..."). Anthropic's system card measures it near 0% at following instructions about the content of its own thinking (figure 6.4.2.4.A). Put any step whose result you need into the visible output, where it can be checked, and set reasoning length with the effort parameter.

Typically this ends at 0–3 examples, not 4–7. The rest of this file is the Haiku 4.5 method. Use it for Haiku 4.5, and for the boundary examples step 3 calls for.

Before Distilling: Check Whether the Task Needs It (2026-07 calibration)

This skill's gap catalog was originally derived from model-card priors. A 2026-07-15 empirical calibration (300 measured Haiku 4.5 calls; data in the agent-routing skill's references/calibration-2026-07-15.md) found Haiku 4.5 substantially stronger than those priors on mechanically checkable work: 240/240 on nested modular arithmetic (16-leaf expression trees), 30-hop function chains, 25-operation state tracking, trap-laden word math, and 5-simultaneous-constraint sentence generation (exact word counts, required/forbidden tokens, a lipogram) — at effort: low, and in one control with chain-of-thought suppressed entirely. On the same battery Sonnet at low effort scored 17/20, missing exact-count constraints Haiku satisfied.

Triage before investing in a full distillation:

1. Output mechanically checkable (schema validates, tests run, counts

count, regex matches)? → A minimal prompt + a deterministic verifier + retry-or-escalate-on-fail is cheaper and more reliable than an example-heavy prompt with no verifier. Spend your effort writing the checker, not the examples. Precision constraints ("exactly N words") held reliably when the prompt defined the counting rule explicitly ("a word = any run of letters or apostrophes") — definitional precision, not scaffolding volume, did the work.

1. Output requires judgment (tone, relevance, quality, ambiguity

resolution)? → This is what the rest of this skill is for. Distill fully: procedures, rubrics, n-shot examples.

1. Mixed? → Split the task. Route the checkable part per (1); distill

only the judgment part.

Iteration warning (measured, same calibration): never ask Haiku to blindly re-improve its own output in a loop. On correct answers, re-application returned the identity (0 changes in 96 loop-pairs); on the one output that did change, quality regressed on the second pass and then froze on the degraded text for all remaining passes. If you iterate, score every iteration with an out-of-band checker or judge, keep argmax, and stop at the first regression.

Activation

When triggered, perform these steps:

1. Extract task context from the conversation: what is the user trying

to accomplish? What domain knowledge applies? What quality criteria matter?

1. Identify the reasoning gaps — what would Opus infer automatically

that Haiku needs spelled out? Common gaps:

• Ambiguity resolution (Opus picks the sensible interpretation; Haiku

needs a decision rule)

• Quality judgment (Opus knows "good enough"; Haiku needs explicit

criteria)

• Edge case handling (Opus reasons through novel situations; Haiku

needs enumerated cases)

• Output calibration (Opus matches tone/length intuitively; Haiku

needs explicit constraints)

1. Generate the distilled prompt following the structure in

Prompt Architecture

1. Add examples. On Haiku 5.5, only at the boundaries a bare run missed

(see Start Bare), usually 0–3. On Haiku 4.5, generate 4–7 diverse examples per Example Design; that was the highest-leverage step there.

1. Audit your example set before delivering. Two checks, both must pass:

• Source-anchoring: for each example output, every concrete fact

(named technology, number, comparison, quoted phrase) is inferrable from that example's input. If you can't reproduce the output knowing only the input, either add the detail to the input or remove it from the output. Invented facts in examples cause Haiku to copy the invention pattern at runtime.

• Length calibration: example output lengths sit inside the stated

output range. If your rule says "60–90 words" but your examples average 35, the rule will not hold — Haiku follows the example central tendency.

If either check fails, regenerate the offending examples before delivering. Examples beat rules; misaligned examples beat aligned rules.

1. Deliver the complete Haiku-ready prompt as a copyable artifact or

file, including system prompt and user prompt components as appropriate

Prompt Architecture

Structure every distilled prompt with these components in this order. Haiku responds best to this specific sequencing:

<role>
[Single sentence: who Haiku is and what it does]
</role>

<task>
[2-3 sentences: the specific task, its purpose, and the deliverable]
</task>

<rules>
[Numbered list of explicit constraints. Be precise about:]
- Output format (JSON schema, markdown structure, etc.)
- Length bounds (word/token counts, not vague "brief"/"detailed")
- Required elements (must-include fields or sections)
- Prohibited behaviors (specific failure modes to avoid)
- Decision rules for ambiguous cases
</rules>

<process>
[Numbered steps. Maximum 7 steps. Each step is one action.]
[Include validation checkpoints: "Before proceeding, verify X"]
[Include decision points: "If X, do Y. If Z, do W."]
</process>

<examples>
[Haiku 5.5: 0-3 boundary examples, each calibrating a judgment rule]
[Haiku 4.5: 4-7 diverse examples; the LARGEST part of the prompt]
[See Example Design section for distribution requirements]
</examples>

<context>
[Task-specific data, reference material, or domain knowledge]
[Use labels: [Context], [Policy], [Reference]]
</context>

Haiku Optimization Rules

Apply these when generating any Haiku-targeted prompt:

Structure & Syntax

• Use XML tags to delimit every section — Haiku respects labeled boundaries
• Keep sentences under 25 words where possible
• One instruction per sentence; split compound instructions
• Use numbered steps, not prose paragraphs, for procedures
• Specify token/word budgets explicitly: "respond in 80-120 words"

Reasoning Support

• Replace open-ended judgment with decision rubrics:

BAD: "Assess whether the code is production-ready" GOOD: "Check: (a) no TODO comments, (b) all functions have error handling, (c) no hardcoded secrets. Score pass/fail per item."

• Bound reasoning depth: "Think in 3-5 steps, then give your answer" (Haiku 4.5; on 5.5 this lands in reasoning it does not take instructions about, see step 7 above)
• Provide a fallback for uncertainty: "If you cannot determine X,

respond with: 'UNCERTAIN: [brief reason]'"

Context Management

• Front-load critical instructions (Haiku attends strongly to position)
• Budget rule of thumb (Haiku 4.5): instructions + rules ≤ 800 tokens, examples get

the rest. For a task processing an 8K document, 3-4K tokens of examples is well within budget and pays for itself in reliability

• Pass only the 1-3 most relevant context snippets, not full documents
• Use explicit delimiters between context and instructions

Output Control

• Require structured output (JSON, labeled sections) for extractable results
• Provide an output template Haiku can fill in
• Specify what comes first in the response: "Begin your response with..."
• For classification tasks, enumerate all valid categories

Failure Prevention

• Anticipate Haiku's common failure modes and add guardrails:
• Hallucination: "Use ONLY information from the provided context.

If the answer is not in the context, say 'Not found in sources.'"

• Verbosity: "Maximum 150 words. Do not add preamble or caveats."
• Format drift: Include the output schema in both rules and examples
• Instruction skipping: Number all constraints; reference them in

the process steps: "Apply rules 2-4 from <rules>"

Example Design

On Haiku 4.5, examples were the single highest-leverage investment. On Haiku 5.5 their job narrows to calibrating judgment rules and showing what to leave unsaid; see Start Bare. The rest of this section is the 4.5 method. Rules tell Haiku what to do; examples show it what "done right" looks like. When rules and examples conflict, Haiku follows the examples. When rules are ambiguous, Haiku extrapolates from examples. This makes examples the primary steering mechanism — not a supplement to rules, but the dominant signal.

Given the economics (see Economics), you should invest heavily here. A prompt with 800 tokens of rules and 3,000 tokens of examples will outperform one with 2,000 tokens of rules and 500 tokens of examples almost every time.

Minimum Example Count: 4 (Haiku 4.5)

For Haiku 4.5, generate 4-7 diverse examples per distilled prompt. Fewer than 4 is under-investing. The marginal cost of each example is negligible compared to the reliability improvement. Use this distribution:

Why the second typical case matters: With only one typical example, Haiku may latch onto incidental features of that example (its length, word choice, domain). A second typical case from a different angle shows Haiku which features are task-relevant and which are coincidental.

Example Format

<example>
<input>
[Realistic input data — use real-world length and complexity]
</input>
<output>
[Exact format Haiku should produce — not a description, the actual output]
</output>
<reasoning>
[1-2 sentences: WHY this output is correct. Which rules applied.
 What Haiku might have gotten wrong without this example.]
</reasoning>
</example>

The `<reasoning>` tag is not optional for complex tasks. It acts as a chain-of-thought anchor, showing Haiku the reasoning pattern to follow. For classification and extraction tasks, reasoning should reference the specific rule numbers that drive the decision.

When the input could be abstract: model the silence

Some tasks (rewriting, summarization, voice/register editing, explanation-from-source) take inputs where the source content is itself abstract — marketing copy, vague descriptions, high-level summaries. These tasks are uniquely prone to a failure mode where Haiku invents concrete details that sound right for the domain but aren't in the source.

Symptom: an output that confidently mentions specifics — algorithm names, technology choices, percentile numbers, version comparisons — not present in the input.

Fix: include an example pair where the input is genuinely abstract and the output explicitly acknowledges what is unspecified, rather than filling the gap with plausible-sounding inferences. Pattern:

<example>
<input>
"We're excited to release our new search backend. We think it's a
massive upgrade over the old one."
</input>
<output>
New search backend released. The announcement does not specify the
underlying changes — whether they affect indexing, ranking, query
parsing, or operational characteristics is not stated. Migration
guidance will follow. The old search path remains available during
transition.
</output>
<reasoning>
The source provides only one factual claim ("released") and one
unverifiable claim ("upgrade"). The output stays at the source's
level of abstraction and explicitly names the categories of
information the source omits, rather than inventing plausible
specifics (algorithm changes, performance numbers, technology names).
</reasoning>
</example>

Pair this with the tagged BAD/GOOD negative example (row 4 in the distribution table above) that demonstrates the exact invention you want to prevent. On a voice-rewrite task, switching from un-anchored examples to this pattern dropped Haiku's architectural-hallucination rate from 95% to 0% (n=25 across two probes).

Example Sizing Guidance (Haiku 4.5)

Context is no constraint here: Haiku 5.5 has a 1M window, though a prompt over 100K tokens is billed at 5× on both sides ($0.50/$2.50 per MTok). The limit is diminishing returns: after 7 examples the marginal benefit drops sharply unless the task has a very large classification space.

Example Quality Criteria

• Examples must be realistic, not toy data — match the complexity and

messiness of real inputs

• Output format must be identical across all examples — Haiku treats

format inconsistency as a signal that format doesn't matter

• Include the hardest case you expect Haiku to handle
• Vary input characteristics: length, complexity, domain, tone
• Never include an example that contradicts your rules
• Order examples from simplest to most complex — this progressive

difficulty helps Haiku build up its understanding

• Source-anchor every concrete fact. Each specific noun, number, or

claim in an example output must be inferrable from that example's input. If your example output invents a plausible architectural detail, Haiku will copy that invention pattern even when its real input doesn't support it. Audit by covering the input and asking: "could I have produced this output knowing only the input?" If not, fix one or the other.

• Match example length to the stated output range. Examples

outweigh rules on length. If your rules say "output 60–90 words" but your examples average 35 words, Haiku will produce ~35 words. Calibrate example output lengths to sit inside (or slightly above) the stated output range.

Delivery Format

Present the distilled prompt in a code block or artifact with clear section markers. Include:

1. System prompt (if applicable): role + persistent rules
2. User prompt template: with {{placeholders}} for variable content
3. Examples: embedded in the prompt or as a separate few-shot section
4. Usage notes: any caveats about when this prompt may fail and what

to watch for

When generating for API use, include the model parameter and recommended settings:

model: claude-haiku-4-5-20251001
max_tokens: [appropriate for task]
temperature: 0 (for deterministic tasks) or 0.3 (for creative tasks)

Agentic Resource Selection

The skill includes two directories of granular reference files. Do NOT read them all. Scan the index below, then read only the files relevant to the current task.

gaps/

Each file documents one reasoning pattern where Haiku diverges from Opus, with a tested mitigation strategy. Read 2-4 per task.

examples/

Complete before/after distillations. Each shows an Opus-level task → Haiku-optimized prompt with annotated examples. Read 1-2 closest to the current task domain.

Self-Check

Before delivering, verify the distilled prompt against these criteria:

• [ ] Every Opus inference is made explicit
• [ ] All constraints are numbered and cross-referenced
• [ ] 4+ diverse examples with consistent output format
• [ ] Examples include: 2 typical, 1+ edge case, 1+ negative/rejection case
• [ ] Example tokens ≥ 2× rule tokens (examples should be the bulk of the prompt)
• [ ] No instruction assumes Haiku will "figure it out"
• [ ] Decision points have explicit branches, not open-ended judgment
• [ ] Output format is demonstrated, not just described
• [ ] <reasoning> tags explain WHY each example output is correct