Write Spec

Write Spec

Produces a tight, review-ready feature spec / PRD from a rough idea, problem statement, or stakeholder request — built for product managers and the engineers, designers, and execs who review their work.

Grounded in: Inspired — Marty Cagan: address value, usability, feasibility, and viability risks; non-goals before solution. Go deeper (The Product Channel): Crafting Killer Problem Statements

When to use this

• A stakeholder or customer dropped a one-line "can we build X?" and you need a real document.
• You have a problem to solve but the solution and scope are still fuzzy.
• You're about to brief engineering/design and need goals, non-goals, and acceptance criteria locked.
• A feature is too big for one spec and you need to phase it (MVP → fast-follow → later).
• You need to align reviewers on success metrics before anyone writes code.

Before you start (gather these)

You need enough to write something true, not generic. Collect:

• The problem — who's hurting, what they can't do today, how you know it's real (data, tickets, quotes).
• The audience / user — which segment(s), and their job-to-be-done.
• The desired outcome — what "better" looks like, ideally as a measurable shift.
• Constraints — deadline, team size, platforms, dependencies, anything off-limits.
• Existing context — current behavior, related features, prior attempts.

If two or more of these are missing or vague, ASK 2-4 sharp clarifying questions before writing. If you already hold this context, skip the questions and instead open the spec with an explicit Assumptions block stating what you took as given, so reviewers can challenge it. Make the questions specific and answerable, e.g.:

• "Who exactly hits this problem — all users, or a segment like new/enterprise/mobile?"
• "What's the one metric that would prove this worked?"
• "What's explicitly out of scope for v1?"
• "Is there a hard deadline or dependency driving timing?"

Don't write a spec on guesses. A spec built on a wrong problem statement wastes a whole team.

Process

1. Restate the problem in one sentence and confirm it. If you can't state it crisply, you don't understand it yet — ask.
2. Write non-goals first. Listing what you're not doing is the fastest way to find the real scope. Every non-goal you name kills a future argument.
3. Set goals, each paired with a metric. A goal without a measurable signal is a wish. If a goal can't be measured, either find a proxy or demote it to a non-goal.
4. Map users and use cases — primary first. Note the edge users you're deliberately not serving in v1.
5. Sketch the solution at the right altitude. Describe behavior and the user experience, not implementation. Leave room for engineering to own how.
6. Write requirements as testable statements. Prefer "The system must X when Y" over adjectives like "fast" or "intuitive." Tag each P0 / P1 / P2.
7. Define acceptance criteria in given/when/then or checklist form — concrete enough that QA and eng can verify them without asking you.
8. Surface risks and open questions honestly. Unknowns hidden now become fire drills later.
9. Phase it if it's big. Cut to the smallest version that delivers the core outcome (MVP), then list fast-follows and later. If the ask fits in one release, skip phasing.
10. Self-check against the Quality bar below, then deliver. Offer a one-page summary up top for exec reviewers.

Output template

Fill this in completely. Replace every [bracket]. Delete sections that genuinely don't apply rather than leaving them empty.

# [Feature name] — Product Spec

**Author:** [name] · **Status:** Draft · **Last updated:** [date]
**Reviewers:** [eng lead, design lead, PM peer, exec sponsor]

## TL;DR
[2-3 sentences: the problem, what we're building, and the one outcome it drives. A reviewer should be able to read only this and get the gist.]

## Problem
[What's broken or missing today, for whom. Lead with evidence: support volume, drop-off rate, sales blockers, user quotes. State the cost of doing nothing.]
- **Evidence:** [metric / ticket count / quote]
- **Why now:** [trigger — deadline, competitor move, strategic bet]

## Goals
[Goals = the outcome targets; Success metrics = how you instrument and measure them. State each number once as a Goal target, then reference (don't restate) it under Success metrics.]
[Each goal has a metric and a target. No metric → not a goal.]
1. [Goal] — measured by [metric], target [number / direction] by [timeframe].
2. [Goal] — measured by [metric], target [number / direction] by [timeframe].

## Non-goals
[What this explicitly does NOT do. Be specific — these are the boundaries reviewers will hold you to. Label each as **permanent** (never in scope) or **deferred (see Phase X)** so deferred items don't read as contradictions with the rollout/phasing section.]
- [Permanent: e.g., "No bulk import — single-record only, by design."]
- [Deferred (see Phase 2): e.g., "Not optimizing for mobile this release."]

## Users & use cases
- **Primary user:** [segment] — job-to-be-done: [what they're trying to accomplish].
- **Secondary user:** [segment] — [their need].
- **Key use cases:**
  1. As a [user], I want to [action] so that [outcome].
  2. As a [user], I want to [action] so that [outcome].
- **Out of scope users:** [segments deliberately not served in v1].

## Solution overview
[Describe the experience and behavior, not the implementation. 1-2 paragraphs + the happy path. Add a wireframe link or ASCII flow if helpful.]

**Happy path:** [Step 1] → [Step 2] → [Step 3] → [outcome].

## Requirements
[Testable statements. Tag priority. Avoid vague adjectives.]

| # | Priority | Requirement |
|---|----------|-------------|
| R1 | P0 | The system must [behavior] when [condition]. |
| R2 | P0 | [Requirement] |
| R3 | P1 | [Requirement] |
| R4 | P2 | [Nice-to-have] |

## Success metrics
- **North-star for this feature:** [the one number that matters].
- **Supporting metrics:** [secondary indicators of health].
- **Guardrail metrics:** [what must NOT get worse — e.g., latency, churn, support load].
- **Measurement plan:** [event/instrumentation needed; where it's tracked].

## Acceptance criteria
[Concrete and verifiable — QA and eng should not need to ask you what "done" means.]
- [ ] Given [context], when [action], then [observable result].
- [ ] Given [context], when [action], then [observable result].
- [ ] Edge case: when [boundary/failure condition], the system [expected behavior].
- [ ] Instrumentation: [event] fires with [properties] on [action].

## Assumptions
[The load-bearing, unvalidated bets this spec rests on — if any is wrong, the spec changes. Distinct from Risks: a risk is something that might go wrong; an assumption is something you're treating as true without proof. Include any "taken as given" context from the Assumptions block above if you skipped clarifying questions.]
- [Assumption — e.g., "Most users hit this from desktop; mobile traffic is negligible."]
- [Assumption — e.g., "The pricing API can return entitlements in under 200ms."]

## Risks & open questions
| Risk / question | Impact | Owner | Status |
|-----------------|--------|-------|--------|
| [What might go wrong or what's unknown] | [High/Med/Low] | [name] | [open / resolved] |

## Rollout / phasing
- **Phase 1 (MVP):** [smallest version that delivers the core outcome]. Gate: [what proves it's ready to expand].
- **Phase 2 (fast-follow):** [next increment].
- **Phase 3 (later):** [deferred scope].
- **Launch plan:** [flag / % rollout / beta cohort], **rollback trigger:** [condition].

## Appendix
- **Dependencies:** [teams, services, third parties].
- **Open design questions:** [link to Figma / docs].
- **References:** [research, related specs, prior art].
- **Changelog:** [date — what changed].

Quality bar

Before delivering, verify every box:

• The problem is stated in one sentence and backed by at least one piece of evidence.
• Every goal has a metric and a target. No bare aspirations.
• Non-goals are explicit and specific — not "we'll figure it out later."
• Requirements are testable statements, not adjectives; each is tagged P0/P1/P2.
• Every acceptance criterion is verifiable by someone other than the author.
• At least one guardrail metric is named (what must not regress).
• Risks and open questions are listed honestly, each with an owner.
• If the scope spans more than one release, it's phased with a clear MVP.
• A reviewer reading only the TL;DR understands what's being built and why.
• No implementation details masquerading as requirements (the "how" is left to eng).

Avoid (anti-patterns)

• A goal with no metric. "Improve the onboarding experience" is a wish. If you can't name the number and the target, it's not a goal and reviewers can't hold you to it.
• Non-goals left blank. This is the section that saves you three scope arguments later. Empty non-goals means every reviewer imagines a different v1.
• Requirements written as adjectives. "Fast", "intuitive", "seamless" are untestable. "Loads in under 400ms at p95" is a requirement.
• Solution before problem. If the Problem section describes a missing feature rather than a user's cost, you specced the answer and skipped the question.
• Acceptance criteria that restate the requirements. They should describe an observable outcome someone could verify without reading your mind.
• Success metrics with no measurement plan. A target nobody has instrumented is a target nobody will report on. Run tracking-plan before you ship.
• Phasing that's really a wish list. If Phase 2 has no trigger and no owner, it's not deferred — it's abandoned, and you should say so in Non-goals instead.

Tips

• Write non-goals before goals. Naming what you won't do is the fastest path to real scope.
• One-pager before full PRD. Get alignment on TL;DR + goals + non-goals first; expand only after reviewers nod.
• If a goal has no metric, it's not a goal — it's a feeling. Find a proxy or cut it.
• Cut to the smallest thing that delivers the core outcome. The MVP is a scoping tool, not a quality compromise.
• Acceptance criteria are a contract with QA. If you'd have to explain "done" in a meeting, the criteria aren't sharp enough.
• Name guardrails early. "Don't make latency or churn worse" prevents shipping a local win that's a global loss.
• Date and version it. Specs are living documents; a stale spec misaligns more than no spec.