build-vs-buy

build-vs-buy is a skill for Claude Code from sethdford/claude-skills. It costs 29 tokens per session (309 once invoked), scanned A, original, MIT.

A framework for deciding whether to build a custom solution, buy an existing product, use open-source software, or combine these approaches.

In plain words
What is it for?
Use it when evaluating tools, services, or frameworks and when comparing requirements, total cost of ownership, vendor risk, technical risk, and team capacity.
Why use it?
It helps expose the full cost and risk of each choice, including development, licensing, operations, training, migration, maintenance, and vendor lock-in.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the decision-making plugin — 8 skills, 3 commands shipped together

Good fit Use it when evaluating tools, services, or frameworks and when comparing requirements, total cost of ownership, vendor risk, technical risk, and team capacity.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sethdford/claude-skills/build-vs-buy
Install

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.

Any agent
npx skills add sethdford/claude-skills --skill build-vs-buy
Clone the repo
git clone --depth 1 https://github.com/sethdford/claude-skills

Made for: Claude Code.

Or install decision-making, the plugin that ships this one along with the rest of its 8 skills, 3 commands.

Wrote 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.

agentmods badge for build-vs-buy

README.md
[![agentmods](https://agentmods.dev/badge/skills/sethdford/claude-skills/build-vs-buy/github.svg)](https://agentmods.dev/skills/sethdford/claude-skills/build-vs-buy)
Your own site
<a href="https://agentmods.dev/skills/sethdford/claude-skills/build-vs-buy"><img src="https://agentmods.dev/badge/skills/sethdford/claude-skills/build-vs-buy/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for build-vs-buy

Your own site · 80×15
<a href="https://agentmods.dev/skills/sethdford/claude-skills/build-vs-buy"><img src="https://agentmods.dev/badge/skills/sethdford/claude-skills/build-vs-buy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 309 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00029 $0.00309
Opus 5 $0.00015 $0.00154
Sonnet 5 $0.00006 $0.00062
Haiku 4.5 $0.00003 $0.00031

Measured 12d ago against content hash 36c3d4f6463d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

build-vs-buy 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 12d 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.

architect/decision-making/skills/build-vs-buy/SKILL.md · 39 lines

What it actually says

Build vs Buy

Systematically compare building custom solutions vs using off-the-shelf products or services.

Context

You are deciding between building custom or buying existing. Establish clear decision criteria and cost models.

Domain Context

Based on make-vs-buy decision frameworks:

  • Build: Full control, learning investment, ongoing maintenance cost
  • Buy: Faster time-to-market, but less control, vendor lock-in risk
  • Hybrid: Use product but customize parts

Instructions

  1. List Requirements: Functional and non-functional needs
  2. Compare Options: Build custom, Product A, Product B, Open source
  3. Cost Model: Development time, licensing, ops, migration, training
  4. Risk Assessment: Vendor risk, technical risk, team capacity risk
  5. Decide: Option with best total cost of ownership wins

Anti-Patterns

  • Build Anything: "We can build it faster!" Result: years and millions later, still building. Guard: Honestly assess dev time vs buying.
  • Vendor Lock-In Ignored: Buy product without exit strategy. Result: stuck. Guard: Evaluate switching cost before committing.

Further Reading

  • Make vs Buy Decision Frameworks
  • Open Source Business Models
Changes

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.

  1. 12d ago First seen · 39 lines · 29 tokens per session scan A 36c3d4f6463d

Subscribe to this mod's changes

build-vs-buy is a skill published in the GitHub repository sethdford/claude-skills (41 stars, last pushed 6mo ago), licensed MIT. It adds 29 tokens to every session and 309 once invoked, about $0.0001 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.

Related

Other skills, from other repositories