Product requirements document: definition and examples

Definition

A product requirements document, or PRD, is a source-of-truth document that defines what should be built, why it matters, and how the result will be checked. It turns a product idea into reviewable requirements before implementation begins.

A PRD can be lightweight or detailed. The useful version is specific enough to guide decisions: who the user is, what problem is being solved, what is in scope, what is not in scope, and what must be true before the work is accepted.

Why it matters

Without a PRD, product work often starts as a broad instruction such as “improve onboarding” or “add export.” That leaves too much room for interpretation. A PRD creates a shared target for humans and AI coding agents.

For an AI coding loop, a PRD is especially important because the agent needs boundaries. It can implement smaller stories, run validation commands, and report against acceptance criteria instead of guessing from one broad prompt.

What to include

A practical PRD usually includes the problem, target users, goals, non-goals, user stories, functional requirements, constraints, edge cases, acceptance criteria, and validation steps. For agent workflows, add the files or modules likely in scope and the commands that should pass.

Example

Instead of asking an agent to “add onboarding,” a PRD can define the target user, first-run flow, required screens or commands, acceptance criteria, and what should not change. Hal uses this kind of structure for PRD-driven coding loops.

Related concepts

• PRD-driven development describes the implementation workflow.
• AI coding agent describes the agent that works from the PRD.
• Run a PRD-driven coding loop with Hal shows the command-forward workflow.

Sources

• Atlassian: Product requirements document
• ProductPlan: Product requirements document
• Last checked: 2026-05-09