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/trtmn/agent-plugins/homebrew-devnpx skills add trtmn/agent-plugins --skill homebrew-devgit clone --depth 1 https://github.com/trtmn/agent-pluginsWhat 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 | $0.00140 | $0.02957 |
| Opus 5 | $0.00070 | $0.01478 |
| Sonnet 5 | $0.00028 | $0.00591 |
| Haiku 4.5 | $0.00014 | $0.00296 |
Grade A, and why
homebrew-dev 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 yesterday.
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 — 403 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Homebrew Packaging Skill
You are an expert at packaging software with Homebrew — both formulas (source builds and pre-built binaries) and casks (macOS apps, fonts, arbitrary files). You help users create, test, and distribute packages through personal taps on GitHub.
Deciding: Formula vs. Cask
| Scenario | Use |
|---|---|
| CLI tool with source code (C, Go, Rust, etc.) | Formula |
| Pre-built binary tarball for a CLI tool | Formula (no build step) |
macOS .app bundle |
Cask |
Font files (.ttf, .otf) |
Cask |
| PKG installer | Cask |
| Arbitrary file placement (e.g. completions, configs) | Cask with artifact |
| App with auto-updater | Cask with auto_updates true |
| Both a CLI and a GUI component | Both (linked from cask with binary) |
Creating a Formula
Scaffold
brew create https://example.com/mytool-1.0.tar.gz
This auto-populates url, sha256, version, and opens the editor.
Key fields
class Mytool < Formula
desc "One-line description (imperative, no trailing period, no 'A' prefix)"
homepage "https://example.com/mytool"
url "https://example.com/mytool-1.0.tar.gz"
sha256 "abc123..." # from: shasum -a 256 <file>
license "MIT"
version "1.0" # omit if parseable from url
depends_on "cmake" => :build # build-time only
depends_on "openssl@3" # runtime
depends_on "[email protected]" => :optional # optional runtime
depends_on :macos => :monterey # minimum macOS
def install
system "./configure", *std_configure_args
system "make", "install"
end
test do
system "#{bin}/mytool", "--version"
assert_match "1.0", shell_output("#{bin}/mytool --version")
end
end
Install directory variables
| Variable | Expands to |
|---|---|
bin |
$(brew --prefix)/bin |
lib |
$(brew --prefix)/lib |
include |
$(brew --prefix)/include |
share |
$(brew --prefix)/share |
etc |
$(brew --prefix)/etc |
var |
$(brew --prefix)/var |
libexec |
$(brew --prefix)/opt/<name>/libexec |
What ships with it
3 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.
- yesterday First seen · 403 lines · 140 tokens per session scan A 1faacc05e195
homebrew-dev is a skill published in the GitHub repository trtmn/agent-plugins (2 stars, last pushed 4d ago), licensed Unlicense. It adds 140 tokens to every session and 2,957 once invoked, about $0.0007 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.
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