What problem does it solve? Product teams often ship features without measurable success criteria, making it impossible to know whether a launch worked. This Skill structures metric design so every PRD and SPEC includes a North Star Metric, supporting input metrics, and health guard rails. ## Core Features & Use Cases - North Star Metric Definition: Guides selection of a single top-level metric that reflects customer value, with templates for SaaS, marketplace, e-commerce, and developer tool business models. - Input Metric Decomposition: Derives 3-5 leading and lagging input metrics across acquisition, activation, engagement, retention, and revenue, each with owner, baseline, and target. - Health Metrics & Guard Rails: Defines thresholds and alert conditions for metrics like error rate, latency, and support tickets that must not degrade while pursuing growth. - Use Case: When writing a PRD for a new onboarding flow, use this Skill to produce a success dashboard with a primary metric, secondary metrics, and guard rails, then link them to measurable acceptance criteria in the SPEC. ## Quick Start Ask the agent to design a North Star Metric, input metrics, and guard rails for your feature and insert them into the PRD's Goals and Success Metrics section.