Practical digital tools for people who build with AI.
For people building with AI agents & Claude Code

The Agent Builder's Toolkit

$19

Make a flaky AI agent reliable. Battle-tested system prompts, tool-definition patterns, an evaluation rubric, and ready-to-run starter agents.

  • 23 reliability-focused system prompts
  • Tool-definition patterns + error-handling checklist
  • Agent evaluation rubric with a 12-prompt test suite
  • 10 copy-paste starter agents
Get it — $19

The Claude Code Power-User Pack

$17

The config layer that turns Claude Code into a disciplined teammate — copy-paste templates, subagents, and deterministic guardrails.

  • 4 CLAUDE.md templates (base + Node/TS, Python, monorepo)
  • 5 ready-to-run subagents (reviewer, debugger, test-writer…)
  • 5 deterministic hooks (block secrets, protect paths, auto-format)
  • 5 custom slash-command skills + annotated settings.json
Get it — $17
They pair up. The Toolkit is the prompt & evaluation layer — how your agent thinks and how you prove it's reliable. The Power-User Pack is the config & guardrail layer — how Claude Code behaves in your repo. Builders who ship agents tend to want both.

New here? Start free 👇

Ship a Reliable AI Agent — the Free Field Guide. The 10-minute version: 7 rules that make an agent reliable, 3 deterministic Claude Code guardrails you can paste today, and a pre-ship checklist. Genuinely useful on its own — no email required.

Read the free guide →

From the blog

Your CLAUDE.md is too long — and that's why Claude Code ignores it. Instruction-following is a budget, not a wishlist. How to audit your CLAUDE.md, give every rule a reason, and graduate the must-happen ones into deterministic hooks — free to read.

Read the article →

Why your AI agent is flaky — and 7 rules that make it reliable. A flaky agent is almost never a model problem; it's a specification problem. Seven concrete rules plus three paste-able Claude Code guardrails — free to read.

Read the article →

About Penloom

Penloom is an independent studio creating clear, genuinely useful digital products — toolkits, templates, and guides — for builders, creators, and small teams. Everything is a one-time digital purchase, delivered by email within minutes, automatically. Questions? Email penloomstudio@gmail.com.