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/pkarpovich/environment/agent-buildernpx skills add pkarpovich/environment --skill agent-buildergit clone --depth 1 https://github.com/pkarpovich/environmentWhat 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 | $0.00074 | $0.01773 |
| Opus 5 | $0.00037 | $0.00886 |
| Sonnet 5 | $0.00015 | $0.00355 |
| Haiku 4.5 | $0.00007 | $0.00177 |
Grade A, and why
agent-builder 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
What ships with it
8 files 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 · 251 lines · 74 tokens per session scan A 0ed311fadf84
agent-builder is a skill published in the GitHub repository pkarpovich/environment (2 stars, last pushed 23d ago), with no licence file. It adds 74 tokens to every session and 1,773 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 2026-08-31.
Other skills, from other repositories
userscripts
Use when writing Tampermonkey/Violentmonkey/Greasemonkey userscripts, modifying website behavior or appearance, or working with .user.js files.
brainstorming
You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
subagent-driven-development
Use when executing implementation plans with independent tasks in the current Pi session using fresh subagents and review loops.
pr
Use when the user wants to create a new pull request, update an existing PR's body, open a draft PR, or preview a PR body locally before pushing.
writing-plans
Use when you have an approved design or requirements for a multi-step task, before touching code.
markdown-formatting
Format and lint markdown and MDX files using markdownlint with comprehensive rule knowledge for automated and manual fixes. Use when working with .md or .mdx files, formatting documentation, linting markdown/MDX, or when user mentions markdown issues, formatting problems, or documentation standards.