Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/geckse/markdown-vdb/prd-methodologynpx skills add geckse/markdown-vdb --skill prd-methodologygit clone --depth 1 https://github.com/geckse/markdown-vdbWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/geckse/markdown-vdb/prd-methodology)<a href="https://agentmods.dev/skills/geckse/markdown-vdb/prd-methodology"><img src="https://agentmods.dev/badge/skills/geckse/markdown-vdb/prd-methodology.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00030 | $0.00524 |
| Opus 5 | $0.00015 | $0.00262 |
| Sonnet 5 | $0.00006 | $0.00105 |
| Haiku 4.5 | $0.00003 | $0.00052 |
Grade A, and why
prd-methodology scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.
PRP Methodology — Quick Reference
The PRP (Product Requirement Prompt) framework is a structured process for creating PRDs that coding agents can execute in a single pass.
Core Principle
A PRD must contain ALL context needed for implementation. If a fresh Claude session with only the PRD can't build the feature correctly, the PRD is incomplete.
The 3-Step Process
- Write initial description — Brain dump what you want: feature, tech stack, constraints, integrations, examples, documentation references
- Generate the PRD — Research the codebase + web, interview the user, produce a structured document following the base template
- Execute the PRD — Clear context, start fresh, implement from the PRD alone
What Makes a Good PRD
DO:
- Reference specific files and code patterns from the codebase
- Write testable validation criteria ("returns 401 on invalid token")
- Include explicit non-goals to prevent scope creep
- List anti-patterns specific to the project
- Order implementation steps by dependency (what must exist before what)
- Include migration strategy for existing data/behavior
DON'T:
- Use vague validation criteria ("works well", "is performant")
- Leave technical design abstract ("use appropriate data structures")
- Assume the implementing agent knows project conventions — spell them out
- Skip the non-goals section — agents will over-build without boundaries
- Write steps that can't be verified independently
Interview Technique
The most valuable part of PRD generation is the interview. Goal: reduce assumptions to near zero.
- Ask at least 8-10 questions before writing
- Batch questions in groups of 3-4
- Provide recommended answers based on codebase research
- Cover: scope, users, technical constraints, data model, compatibility, edge cases, testing, anti-patterns
- Final question: "What else should I know that I haven't asked about?"
Validation Criteria Standards
Every criterion must be:
- Specific: "Login with wrong password returns 401" not "error handling works"
- Testable: Can be verified by running a command or checking output
- Independent: Each criterion can be checked on its own
- Complete: Cover happy path, edge cases, backward compatibility, and security
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago First seen · 56 lines · 30 tokens per session scan A 2f6b2ca69f45
prd-methodology is a skill published in the GitHub repository geckse/markdown-vdb (23 stars, last pushed 20d ago), licensed MIT. It adds 30 tokens to every session and 524 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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