From Idea to Spec: Documenting Your MVP Requirements
January 17, 2025 11 min read
# From Idea to Spec: Documenting Your MVP Requirements
Slug: from-idea-to-spec-documenting-requirements
Date: 2024-03-27
Tag: MVP Development
Meta Description: Learn how to transform your product idea into a clear specification document. Practical templates and examples for documenting MVP requirements that developers can actually build from.
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The gap between "I have an idea" and "developers can build this" is where most MVP projects stumble. The idea lives in your head with perfect clarity. The spec needs to transfer that clarity to people who've never seen your vision.
Founders often underestimate this translation. They assume developers will "just get it" after a conversation. Then three weeks into development, the team delivers something that technically matches the requirements but completely misses the point.
Good requirements documentation isn't bureaucratic overhead. It's the artifact that aligns everyone around what you're actually building. This guide walks through how to create that artifact, what to include, and common documentation mistakes that derail projects.
Why Documentation Exists
Requirements documentation serves three purposes:
Alignment: Everyone involved—you, your co-founders, your developers, your designer—agrees on what you're building. Disagreements surface during documentation, when they're cheap to resolve, rather than during development, when they're expensive.
Accountability: When scope questions arise ("should this button do X or Y?"), the document provides answers. Without documentation, these questions interrupt development or get answered inconsistently.
Stop planning and start building. We turn your idea into a production-ready product in 6-8 weeks.
Continuity: People leave projects, take vacations, or forget conversations. The document persists. Six months from now, you can check why a decision was made.
The document isn't a legal contract. It's a shared reference point. It should be comprehensive enough to build from but flexible enough to update as you learn.
Starting With the Problem, Not the Solution
Before writing features, write down the problem you're solving. This seems obvious, but founders routinely skip it—jumping straight to solutions.
The Problem Statement
A good problem statement answers:
Who has this problem? Be specific. "Small business owners" is too vague. "Service professionals who spend 3+ hours weekly on manual scheduling" is actionable.
What is the problem? Describe the pain. What are they doing now? Why doesn't it work?
Why does it matter? What's the cost of the problem remaining unsolved? Time? Money? Frustration?
Why hasn't it been solved? What have people tried? Why did it fail?
Example:
Problem Statement
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Freelance personal trainers spend 5-10 hours weekly managing client scheduling. They use a combination of text messages, phone calls, and paper calendars. Double-bookings happen regularly, causing client frustration and lost revenue.
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Existing scheduling tools are designed for businesses with fixed locations. Trainers who work across multiple gyms and client homes need location-aware scheduling that existing tools don't provide.
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The cost: trainers limit their client load not because of time, but because of scheduling complexity. Each booking error costs approximately $50-150 in lost sessions or makeup sessions.
This statement guides every feature decision. When someone asks "should we add group class scheduling?", you can evaluate it against the core problem.
User Personas
Who specifically will use this product? Personas make abstract users concrete.
A persona includes:
Name and role: Give them an identity
Goals: What are they trying to accomplish?
Frustrations: What blocks them currently?
Technical comfort: How sophisticated are they with software?
Context of use: When and where do they use tools like this?
Example:
Persona: Maria, Independent Personal Trainer
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Maria has been a personal trainer for 8 years. She has 15-20 regular clients and works across three gym locations plus home visits. She earns $60-100 per session.
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Goals: Maximize sessions per week without administrative overhead. Maintain strong client relationships.
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Frustrations: Text message scheduling leads to missed messages. She's double-booked herself twice this month. She has no visibility into next month's income.
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Technical comfort: Uses iPhone comfortably. Has tried Google Calendar but found it insufficient for multi-location scheduling.
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Context: Checks phone between sessions. Often scheduling while at the gym. Needs quick actions, not complex workflows.
With problem and users defined, document what you're building. This is the bulk of the spec.
Feature List Format
Each feature needs:
Name: A clear, consistent name used everywhere. Not "the scheduling thing"—"Session Booking."
Description: One to two sentences explaining what this feature does and why it matters.
User Story: Who uses this, what they do, and why. Format: "As a [user type], I want to [action] so that [benefit]."
Acceptance Criteria: How do we know this feature is complete? Bullet list of specific conditions.
Priority: Is this Must Have, Should Have, Could Have, or Won't Have for MVP?
Dependencies: What other features must exist for this to work?
Example:
Feature: Session Booking
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Description: Clients can book available time slots with their trainer. The booking considers trainer availability, client preferences, and location logistics.
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User Story: As a client, I want to book my next training session online so that I don't have to coordinate via text messages.
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Acceptance Criteria:
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- Client can view trainer's available slots for the next 4 weeks
- Slots show location options (client home, gym locations)
- Client can select a slot and confirm booking
- Both client and trainer receive confirmation email
- Slot becomes unavailable to other clients immediately upon booking
Features don't exist in isolation. Document how users move through your product.
A user flow maps the steps from trigger to outcome:
Flow: New Client Books First Session
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1. Client receives invite link from trainer (via text or email)
2. Client opens link, sees trainer profile and available times
3. Client creates account (email, name, phone)
4. Client selects preferred time and location
5. Client confirms booking
6. Client receives confirmation email with calendar invite
7. Trainer receives notification of new booking
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Alternate paths:
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- If no times work: Client can request alternative times (triggers message to trainer)
- If client already has account: Skip step 3
User flows reveal gaps that feature lists miss. "Wait, how does the trainer get the client's address for home visits?" These questions are better answered in documentation than during development.
Edge Cases and Error Handling
What happens when things go wrong? Document explicitly:
Booking Edge Cases
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- Client tries to book a slot someone else just booked: Show error, refresh availability, prompt to select different time
- Trainer becomes unavailable after slot is booked: Notify client, offer rescheduling or cancellation
- Client's payment method fails: (v1: no payment collection, clients pay in person)
- Client wants to book outside available hours: Cannot—show only available times
Edge cases are where products feel polished or broken. Thinking them through during documentation prevents awkward gaps in the finished product.
Technical Requirements
Some requirements aren't features but constraints on how features work.
Performance Requirements
How fast does it need to be? Be specific:
Page load: Under 3 seconds on mobile networks
Search results: Under 1 second
Booking confirmation: Under 2 seconds
Without stated requirements, developers make their own tradeoffs. Sometimes those tradeoffs are fine. Sometimes they result in painfully slow experiences.
Security Requirements
What data sensitivity exists? What protection is needed?
Authentication: Email/password login, session duration 7 days
Password requirements: Minimum 8 characters, no complexity requirements
Data access: Trainers see only their own clients. Clients see only their own bookings.
Data encryption: SSL in transit, at-rest encryption for PII
Integration Requirements
What external services must you connect to?
Email: Transactional emails via SendGrid or similar
Calendar sync: Google Calendar export (future: bidirectional sync)
SMS notifications: Twilio for booking reminders (v2)
For each integration, note whether it's required for launch or a future enhancement.
Platform Requirements
Where does this run?
Web application: Responsive design for mobile and desktop
Browser support: Last 2 versions of Chrome, Safari, Firefox; Edge current version
Mobile: No native app for v1 (web is mobile-friendly)
Non-Functional Requirements
Beyond features and technical constraints, document how the product should behave:
Accessibility
WCAG compliance level: 2.1 AA (standard for most web applications)
Screen reader support: Yes, core flows must be navigable
Keyboard navigation: Yes, for all interactive elements
Reliability
Uptime target: 99.5% (approximately 3.5 hours downtime per month acceptable)
Data backup: Daily backups with 30-day retention
Disaster recovery: Able to restore from backup within 4 hours
Scalability
Expected users at launch: 50-100 trainers, 500-1000 clients
Growth expectation: 10x in first year
Architecture implications: Standard deployment sufficient for v1; evaluate scaling needs before 500 trainers
These requirements might seem premature for an MVP. They're not. They inform architecture decisions that are expensive to change later.
What Not to Include
Good documentation is comprehensive but focused. Leave out:
Implementation details: Don't specify that the database should use PostgreSQL or the frontend should be React. State what you need; let the development team determine how.
Visual design: Unless you have specific design requirements, leave aesthetics to the design phase. Describing button colors and fonts wastes documentation time.
Marketing copy: The requirements document is internal. Save the compelling narrative for your website.
Wishlist features: Include only what's being built in this phase. A "future ideas" appendix is fine, but don't let it bloat the core document.
Common Documentation Mistakes
Assumed Context
You've thought about your product for months. Developers are seeing it for the first time. Don't assume they know:
Your industry's terminology
Why certain decisions were made
Who your competitors are
What you've tried before
Explain context explicitly. "We considered X but rejected it because Y" is useful information.
Vague Acceptance Criteria
"Users should be able to book sessions easily" isn't testable. "Users can complete booking in under 60 seconds and with fewer than 4 clicks" is testable.
Every acceptance criterion should be verifiable. If you can't test whether it's met, rewrite it until you can.
Missing Error States
Documentation often describes the happy path: everything works as intended. Real users take wrong turns, have bad internet connections, and input invalid data.
For every feature, ask: "What if this fails? What does the user see?"
Scope Without Priority
A long feature list without prioritization creates the illusion that everything is equally important. It's not. If the budget or timeline gets cut, which features survive?
Priority forces hard decisions before development starts, when you can make them rationally instead of under pressure.
Documentation as Afterthought
Some founders write requirements during development, documenting what was built rather than what should be built. This defeats the purpose.
Requirements documentation should be complete before development begins. Updates during development are fine—new learning should be captured—but the foundation needs to exist first.
Template: Minimum Viable Documentation
For a straightforward MVP, your documentation might be 10-20 pages. Here's the structure:
1. Executive Summary (1 page)
What is this product?
Who is it for?
What problem does it solve?
2. Problem Definition (2-3 pages)
Problem statement
User personas (2-3 personas)
Current alternatives and their limitations
3. Feature Specification (5-10 pages)
Feature list with priorities
Detailed specifications for Must Have features
Brief descriptions for Should Have features
User flows for critical journeys
4. Technical Requirements (2-3 pages)
Platform requirements
Performance requirements
Security requirements
Integration requirements
5. Out of Scope (1 page)
Explicitly excluded features
Future considerations
6. Open Questions (1 page)
Decisions still to be made
Assumptions requiring validation
Working With Your Document
The requirements document isn't finished when you write it. It's a living artifact.
Review with stakeholders: Anyone who has input on the product should review the document before development. Surface disagreements now.
Review with developers: Your development team may identify technical issues, missing requirements, or unrealistic expectations. Their feedback improves the document.
Update as you learn: Development reveals gaps. User feedback shifts priorities. Update the document rather than maintaining separate notes.
Version the document: When requirements change, note what changed and why. History helps when you later wonder how you ended up here.
Key Takeaways
Transforming an idea into a buildable spec requires:
Starting with the problem: Clear problem definition guides every feature decision
Defining specific users: Personas make abstract users concrete and prevent designing for no one
Documenting features completely: Names, descriptions, stories, and testable acceptance criteria
Mapping user journeys: Flows reveal gaps that feature lists miss
Stating constraints explicitly: Performance, security, and platform requirements inform architecture
Prioritizing ruthlessly: Not everything is equally important; the document should reflect that
Good documentation takes time—typically several days of focused work. That investment prevents weeks of misalignment during development.
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