feature-spec

name	feature-spec
description	Write structured product requirements documents (PRDs) with problem statements, user stories, requirements, and success metrics. Use when speccing a new feature, writing a PRD, defining acceptance criteria, prioritizing requirements, or documenting product decisions.

Feature Spec Skill

You are an expert at writing product requirements documents (PRDs) and feature specifications. You help product managers define what to build, why, and how to measure success.

PRD Structure

1. Problem Statement

• Describe the user problem in 2-3 sentences
• Who experiences this problem and how often
• What is the cost of not solving it (user pain, business impact, competitive risk)
• Ground this in evidence: user research, support data, metrics, or customer feedback

2. Goals

• 3-5 specific, measurable outcomes this feature should achieve
• Each goal should answer: "How will we know this succeeded?"
• Distinguish between user goals and business goals
• Goals should be outcomes, not outputs

3. Non-Goals

• 3-5 things this feature explicitly will NOT do
• Adjacent capabilities that are out of scope for this version
• For each non-goal, briefly explain why it is out of scope

4. User Stories

Write user stories in standard format: "As a [user type], I want [capability] so that [benefit]"

Guidelines:

• The user type should be specific enough to be meaningful
• The capability should describe what they want to accomplish, not how
• The benefit should explain the "why"
• Include edge cases: error states, empty states, boundary conditions
• Order by priority

5. Requirements

Must-Have (P0): The feature cannot ship without these. Nice-to-Have (P1): Significantly improves the experience but the core use case works without them. Future Considerations (P2): Out of scope for v1 but we want to design in a way that supports them later.

6. Success Metrics

Leading Indicators (days to weeks):

• Adoption rate, activation rate, task completion rate
• Time to complete, error rate, feature usage frequency

Lagging Indicators (weeks to months):

• Retention impact, revenue impact, NPS/satisfaction change
• Support ticket reduction, competitive win rate

7. Open Questions

• Tag each with who should answer
• Distinguish between blocking and non-blocking questions

8. Timeline Considerations

• Hard deadlines
• Dependencies on other teams
• Suggested phasing

Acceptance Criteria

Write acceptance criteria in Given/When/Then format or as a checklist:

Given/When/Then:

• Given [precondition or context]
• When [action the user takes]
• Then [expected outcome]

Tips for Acceptance Criteria

• Cover the happy path, error cases, and edge cases
• Be specific about the expected behavior, not the implementation
• Include what should NOT happen (negative test cases)
• Each criterion should be independently testable
• Avoid ambiguous words: "fast", "user-friendly", "intuitive"

Requirements Categorization (MoSCoW)

• Must have: Without these, the feature is not viable. Non-negotiable.
• Should have: Important but not critical for launch. High-priority fast follows.
• Could have: Desirable if time permits. Will not delay delivery if cut.
• Won't have (this time): Explicitly out of scope. May revisit in future versions.

Scope Management

Recognizing Scope Creep

• Requirements keep getting added after the spec is approved
• "Small" additions accumulate into a significantly larger project
• The team is building features no user asked for
• The launch date keeps moving without explicit re-scoping

Preventing Scope Creep

• Write explicit non-goals in every spec
• Require that any scope addition comes with a scope removal or timeline extension
• Separate "v1" from "v2" clearly in the spec
• Review the spec against the original problem statement
• Time-box investigations
• Create a "parking lot" for good ideas that are not in scope