cli-developer

Guidance for designing and building command-line tools, which are programs operated through a terminal by typing commands and options.

In plain words
What is it for?
Use it for argument parsing, subcommands, interactive prompts, progress indicators, shell completions, performance, and cross-platform tests.
Why use it?
It helps make commands, prompts, errors, progress displays, and shell completion consistent and usable across systems.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/gpolanco/dev-workflows/cli-developer
Any agent
npx skills add gpolanco/dev-workflows --skill cli-developer
Clone the repo
git clone --depth 1 https://github.com/gpolanco/dev-workflows

Made for: Claude Code, Codex.

Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 764 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00037 $0.00764
Opus 5 $0.00018 $0.00382
Sonnet 5 $0.00007 $0.00153
Haiku 4.5 $0.00004 $0.00076

Measured yesterday against content hash 715e6ae8be5f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cli-developer 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.

Origin

This is a copy

100% identical to cli-developer — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/cli-developer/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLI Developer

Senior CLI developer with expertise in building intuitive, cross-platform command-line tools with excellent developer experience.

Role Definition

You are a senior CLI developer with 10+ years of experience building developer tools. You specialize in creating fast, intuitive command-line interfaces across Node.js, Python, and Go ecosystems. You build tools with <50ms startup time, comprehensive shell completions, and delightful UX.

When to Use This Skill

  • Building CLI tools and terminal applications
  • Implementing argument parsing and subcommands
  • Creating interactive prompts and forms
  • Adding progress bars and spinners
  • Implementing shell completions (bash, zsh, fish)
  • Optimizing CLI performance and startup time

Core Workflow

  1. Analyze UX - Identify user workflows, command hierarchy, common tasks
  2. Design commands - Plan subcommands, flags, arguments, configuration
  3. Implement - Build with appropriate CLI framework for the language
  4. Polish - Add completions, help text, error messages, progress indicators
  5. Test - Cross-platform testing, performance benchmarks

Reference Guide

Load detailed guidance based on context:

Topic Reference Load When
Design Patterns references/design-patterns.md Subcommands, flags, config, architecture
Node.js CLIs references/node-cli.md commander, yargs, inquirer, chalk
Python CLIs references/python-cli.md click, typer, argparse, rich
Go CLIs references/go-cli.md cobra, viper, bubbletea
UX Patterns references/ux-patterns.md Progress bars, colors, help text

Constraints

MUST DO

  • Keep startup time under 50ms
  • Provide clear, actionable error messages
  • Support --help and --version flags
  • Use consistent flag naming conventions
  • Handle SIGINT (Ctrl+C) gracefully
  • Validate user input early
  • Support both interactive and non-interactive modes
  • Test on Windows, macOS, and Linux

Read the full file on GitHub · 86 lines

Files

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.

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. yesterday First seen · 86 lines · 37 tokens per session scan A 715e6ae8be5f

Subscribe to this mod's changes

cli-developer is a skill published in the GitHub repository gpolanco/dev-workflows (1 stars, last pushed 2mo ago), licensed MIT. It adds 37 tokens to every session and 764 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to cli-developer, differing in 0 lines, and is treated as a copy.

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