Agentic Plugin Marketplace is a collection of reusable plugins, agents, skills, commands, and rules for coding-agent tools including Claude Code, Codex CLI, Cursor, OpenCode, Antigravity CLI, and GitHub Copilot. It is for developers assembling agentic workflows across multiple harnesses from shared Markdown sources, and the catalogue entries are examples or subsets of those workflow components.
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 skills add wshobson/agents --skill before-you-buildgit clone --depth 1 https://github.com/wshobson/agentsWrote 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/wshobson/agents/before-you-build)<a href="https://agentmods.dev/skills/wshobson/agents/before-you-build"><img src="https://agentmods.dev/badge/skills/wshobson/agents/before-you-build.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 5.1 | $0.00075 | $0.00569 |
| Opus 5 | $0.00037 | $0.00284 |
| Sonnet 5 | $0.00015 | $0.00114 |
| Haiku 4.5 | $0.00007 | $0.00057 |
Grade A, and why
before-you-build 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 3d 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 — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Before You Build
Run a compact pre-mortem before implementation. The goal is not to block building; it is to identify the highest-risk assumption, the smallest validation step, and the build scope that should be delayed until evidence improves.
When To Use
Use this skill when a user asks to build or ship:
- A new product, MVP, prototype, landing page, SaaS app, marketplace, content site, agent workflow, or internal tool
- A major feature with unclear adoption, revenue, retention, trust, or distribution impact
- A public launch asset where weak positioning could waste development or promotion effort
Skip this skill when the task is a narrow implementation fix, refactor, test repair, dependency update, or already-validated change with clear acceptance criteria.
Risk Checklist
Review the idea across these risks:
- Demand: Is there evidence that a specific buyer or user urgently wants this?
- Positioning: Can the target user understand what it is and why it matters in one sentence?
- Monetization: Is there a credible path to payment, budget, or strategic value?
- Retention: Is there a reason users would return after the first try?
- Trust: Does the product require credibility, data access, integrations, or behavior change that users may resist?
- Distribution: Is there a repeatable way to reach the target user?
- Feature adoption: For feature work, will the feature change user behavior or just add surface area?
If the verdict is not obvious, use references/risk-checklist.md for deeper questions.
Output Format
Keep the response short and decision-oriented:
- Risk verdict: Low, medium, or high risk, with one sentence explaining why.
- Main assumption: The single assumption most likely to break the project.
- Evidence to find first: The smallest useful signal before building more.
- Do next: One concrete validation step or reduced build scope.
- Delay: What not to build yet.
Guidance
- Be direct about weak evidence, but avoid dismissing the user's idea.
- Prefer smaller validation steps over large research plans.
- Separate product risk from engineering difficulty.
- If the idea is already validated, say what evidence makes it lower risk and suggest the smallest implementation slice.
- If facts are missing, name the missing evidence instead of inventing market claims.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago First seen · 51 lines · 75 tokens per session scan A e5ce9fc6e4ef
before-you-build is a skill published in the GitHub repository wshobson/agents (39,461 stars, last pushed 5d ago), licensed MIT. It adds 75 tokens to every session and 569 once invoked, about $0.0004 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 2026-09-03.
Other skills, from other repositories
weather-retrieval
Retrieve current weather information for a specific location. Use when a user asks for weather, temperature, conditions, forecast summary, or climate details for a city, region, or place.
arithmetic-evaluator
Evaluate arithmetic expressions and return numeric results. Use when a user asks an arithmetic question, requests calculation, or provides a math expression involving numbers, parentheses, and arithmetic operators.
returns-policy
Answer return, refund, and warranty questions for electronics. Use when the user mentions returns, refunds, RMAs, warranty coverage, damaged items, or opened packaging.
technical-troubleshooting
Provide setup, troubleshooting, and maintenance guidance. Use when the user reports a device that won't power on, connectivity issues, setup questions, overheating, or maintenance concerns.
api-interface-design
Use when designing public APIs, module boundaries, provider adapters, tool schemas, or data contracts.
explore
Explore the codebase and summarize how the project is wired.