Stage 3: Product Definition
Overview
Product Definition transforms Discovery outputs into actionable specifications. This stage focuses on creating product requirements documents, formalizing architecture decisions, and validating that product direction aligns with business needs.
When You Enter This Stage
You enter Product Definition after completing Stage 2: Discovery with a finalized BRD.
NOTE
Prerequisites: BRD complete and available at docs/brds/. Architecture options explored during Discovery.
Available Tools
| Tool | Type | How to Invoke | Purpose |
|---|---|---|---|
| prd-builder | Agent | Select prd-builder agent | Create product requirements documents from BRDs |
| product-manager-advisor | Agent | Select product-manager-advisor agent | Get product management guidance and feedback |
| adr-creation | Agent | Select adr-creation agent | Document architecture decisions formally |
| arch-diagram-builder | Agent | Select arch-diagram-builder agent | Generate architecture diagrams for PRDs |
| security-plan-creator | Agent | Select security-plan-creator agent | Validate security requirements in product specs |
Design Thinking for Product Concepts
Teams that used dt-coach during Discovery can carry Design Thinking outputs into Product Definition. Methods 4-5 (Brainstorming and User Concepts) produce validated solution concepts with Desirability/Feasibility/Viability analysis that strengthen PRD requirements. The dt-coach agent helps refine concepts before formal PRD creation, ensuring product definitions reflect user-validated insights. See the Design Thinking documentation for method details.
Role-Specific Guidance
TPMs own Product Definition, translating BRDs into PRDs with clear acceptance criteria. Tech Leads contribute architecture decisions and validate technical feasibility of proposed requirements.
Starter Prompts
Select prd-builder agent:
Create a PRD from the BRD at docs/brds/fleet-management-v1.md. Define
the vehicle tracking dashboard requirements with acceptance criteria for
real-time GPS updates, geofence alerting, and non-functional requirements
for sub-500ms map tile rendering at 10,000 concurrent sessions.
Select adr-creation agent:
Document the architecture decision for choosing PostgreSQL over CosmosDB
for the order management service. Include decision drivers around query
complexity and transaction support, alternatives considered, and the
migration path from the existing MongoDB deployment.
Select arch-diagram-builder agent:
Generate an architecture diagram for the event-driven order processing
pipeline. Show the message flow from API gateway through the event bus
to worker services, including the dead-letter queue and monitoring
integration. Use mermaid flowchart syntax.
Stage Outputs and Next Stage
Product Definition produces PRDs, ADRs, and architecture diagrams. Transition to Stage 4: Decomposition when PRDs and ADRs are finalized.
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