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The Hard Parts.dev
EP-05 Ai EP Engineering Playbook
Difficulty high Owner · evaluation owner

Evaluate an AI feature against real tasks

Evaluate the feature against real user jobs, realistic failure patterns, and operational constraints so the team learns whether the system actually helps, not just whether it performs well on curated examples.

Difficulty
high
Time horizon
days to define, weeks to gather useful evidence
Primary owner
evaluation owner
Confidence
high
At a glanceEP-05
Situation
An AI feature needs evaluation beyond synthetic benchmarks or generic demos.
Goal
Replace proxy confidence with task-grounded evidence about usefulness, correctness, risk, and failure behavior.
Do not use when
the feature is still too undefined to know what task it serves
Primary owner
evaluation owner
Roles involved

AI engineerproduct ownerevaluation ownerdomain expertsrepresentative users or user proxiesrisk or quality partner when needed

Context

The situation

Deciding whether to reach for this playbook: when it fits, and when it doesn't.

Use when

Conditions where this playbook is the right tool.

  • A team is deciding whether an AI feature is ready to ship or scale
  • Benchmarks look good but user value is uncertain
  • Real-world behavior matters more than lab performance
  • The system affects workflow quality, accuracy, or decision-making

Stakes

Why this matters

What this playbook protects against, and why skipping or half-running it tends to be expensive.

AI features often fail in the gap between benchmark success and actual work. Real evaluation reveals whether the feature helps on the messy edges: ambiguous prompts, incomplete evidence, user misuse, changing context, and operational pressure.

Quality bar

What good looks like

The observable qualities of a team or system that is actually doing this well. Not just going through the motions.

Signs of the playbook done well

  • Evaluation is tied to concrete user tasks and success criteria
  • The team knows the feature’s strong cases, weak cases, and unsafe cases
  • Measurement includes usefulness, failure shape, and review burden
  • Go/no-go decisions are legible and evidence-based
  • Benchmark results are contextualized instead of treated as truth

Preparation

Before you start

What you need available and true before running the procedure. Skipping this is the most common reason playbooks fail.

Inputs

Material you'll want to gather first.

  • Feature scope
  • Target user personas and tasks
  • Representative prompts or inputs
  • Ground truth or review criteria where possible
  • Benchmark results if available
  • Human workflow expectations

Prerequisites

Conditions that should be true for this to work.

  • The team knows what user task the feature claims to improve
  • There is access to realistic task examples
  • Someone owns the evaluation design rather than treating it as a side job

Procedure

The procedure

Each step carries its purpose (why it exists), its actions (what you do), and its outputs (what you produce). Read the purpose. It's what keeps the step from degenerating into checklist theatre.

  1. Define the real task and failure cost

    Make evaluation answer the right question.

    Actions

    • Write the task in user terms, not model terms
    • Define what good, acceptable, weak, and harmful performance look like
    • State what kinds of failure matter most

    Outputs

    • Task evaluation definition
  2. Assemble representative task cases

    Prevent evaluation from overfitting to convenience examples.

    Actions

    • Collect real or realistic examples spanning common, tricky, and edge cases
    • Include ambiguity, incomplete context, and failure-prone scenarios
    • Tag the cases by risk, domain, and expected behavior

    Outputs

    • Task case set
  3. Measure outcome, not just output

    Check whether the feature improves the workflow.

    Actions

    • Evaluate answer quality, user effort reduction, review burden, and decision confidence
    • Measure where human correction is needed and how often
    • Compare against baseline workflow, not only against itself

    Outputs

    • Task outcome scorecard
  4. Analyze failure shape

    Understand how the feature goes wrong, not just how often.

    Actions

    • Cluster errors into categories like omission, hallucination, overconfidence, bad retrieval, or unsafe shortcut
    • Identify failure cases that users are unlikely to catch
    • Separate tolerable errors from unacceptable ones

    Outputs

    • Failure taxonomy
  5. Make an evidence-based shipping decision

    Tie launch decisions to task reality.

    Actions

    • State where the feature is ready, limited, or unsafe
    • Define mitigations such as stronger review, narrower scope, or better retrieval
    • Record what evidence would justify broader rollout later

    Outputs

    • Shipping recommendation

Judgment

Judgment calls and pitfalls

The places where execution actually diverges: decisions that need thought, questions worth asking, and mistakes that recur regardless of good intent.

Decision points

Moments where judgment and trade-offs matter more than procedure.

  • What user task are we truly evaluating?
  • What failure is unacceptable even at low frequency?
  • Does the feature reduce user effort enough to justify its new risks?
  • Where should this feature be limited or gated?

Questions worth asking

Prompts to use on yourself, the team, or an AI assistant while running the procedure.

  • What real user job does this feature improve?
  • Which failures matter most because users will not catch them?
  • How does this compare to the current workflow, not just to a benchmark?

Common mistakes

Patterns that surface across teams running this playbook.

  • Evaluating generic helpfulness instead of a concrete job
  • Overfitting evaluation to easy examples
  • Using benchmark lifts as a substitute for workflow evidence
  • Ignoring the cost of human review or correction

Warning signs you are doing it wrong

Signals that the playbook is being executed but not landing.

  • The team can quote eval scores but not real task outcomes
  • The feature performs well in demos and poorly in messy use
  • Failure discussions focus on rate but not on detectability or harm
  • Shipping decisions happen before failure shape is understood

Outcomes

Outcomes and signals

What should exist after the playbook runs, how you'll know it worked, and what to watch for over time.

Artifacts to produce

Durable outputs the playbook should leave behind.

  • Task evaluation definition
  • Task case set
  • Task outcome scorecard
  • Failure taxonomy
  • Shipping recommendation

Success signals

Observable changes that mean the playbook landed.

  • The team understands where the feature truly helps
  • Unsafe or low-value use cases are identified before broad rollout
  • Task-grounded evaluation changes design or launch decisions
  • Benchmark discussion becomes secondary to workflow evidence

Follow-up actions

Moves that keep the playbook's effects compounding after it finishes.

  • Refresh the case set as real usage broadens
  • Connect repeated failure classes to model, retrieval, or UX changes
  • Track whether live behavior matches pre-launch task evaluation

Metrics or signals to watch

Longer-horizon indicators that the underlying problem is receding.

  • Task success rate
  • Human correction rate
  • Review or validation time per output
  • Unacceptable failure frequency
  • User trust or usefulness ratings by task

AI impact

AI effects on this playbook

How AI-assisted and AI-driven workflows help execution, and the ways they can make it worse.

AI can help with

Where AI tooling genuinely reduces the cost of running this playbook well.

  • Drafting case taxonomies and evaluation sheets
  • Clustering failure patterns from evaluation runs
  • Summarizing differences between benchmark and task-grounded outcomes

AI can make worse by

Distortions AI introduces that make the underlying problem harder to see.

  • Generating synthetic cases that are too clean
  • Masking weak task fit behind persuasive evaluation summaries
  • Inflating apparent rigor with more metrics that still miss user reality

Relationships

Connected playbooks

Failure modes this playbook tends to address, decisions behind the situation, red flags that motivate running it, and neighboring playbooks.