cli-developer skill

by Jeffallan·Jeffallan/claude-skills·12k stars·MIT

Use when building CLI tools, implementing argument parsing, or adding interactive prompts. Invoke for parsing flags and subcommands, displaying progress bars and spinners, generating bash/zsh/fish completion scripts, CLI design, shell completions, and cross-platform terminal applications using commander, click, typer, or cobra.

A100/100content scan

Is the cli-developer skill safe?

Clean: nothing in its files matched our rules. We read 6 files in the folder on 2026-09-28.

No findings.

Install the cli-developer skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description.

git clone --depth 1 https://github.com/Jeffallan/claude-skills.git /tmp/claude-skills
mkdir -p ~/.claude/skills
cp -r /tmp/claude-skills/skills/cli-developer ~/.claude/skills/cli-developer

available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

CLI Developer

Core Workflow

Analyze UX — Identify user workflows, command hierarchy, common tasks. Validate by listing all commands and their expected --help output before writing code.
Design commands — Plan subcommands, flags, arguments, configuration. Confirm flag naming is consistent and no existing signatures are broken.
Implement — Build with the appropriate CLI framework for the language (see Reference Guide below). After wiring up commands, run --help to verify help text renders correctly and --version to confirm version output.
Polish — Add completions, help text, error messages, progress indicators. Verify TTY detection for color output and graceful SIGINT handling.
Test — Run cross-platform smoke tests; benchmark startup time (target: <50ms).

Reference Guide

Load detailed guidance based on context:

Quick-Start Example

Node.js (commander)

#!/usr/bin/env node
// npm install commander
const { program } = require('commander');

program
  .name('mytool')
  .description('Example CLI')
  .version('1.0.0');

program
  .command('greet <name>')
  .description('Greet a user')
  .option('-l, --loud', 'uppercase the greeting')
  .action((name, opts) => {
    const msg = `Hello, ${name}!`;
    console.log(opts.loud ? msg.toUpperCase() : msg);
  });

program.parse();

For Python (click/typer) and Go (cobra) quick-start examples, see references/python-cli.md and references/go-cli.md.

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

MUST NOT DO

Block on synchronous I/O unnecessarily — use async reads or stream processing instead.
Print to stdout when output will be piped — write logs/diagnostics to stderr.
Use colors when output is not a TTY — detect before applying color:

// Node.js
  const useColor = process.stdout.isTTY;

# Python
  import sys
  use_color = sys.stdout.isatty()

// Go
  import "golang.org/x/term"
  useColor := term.IsTerminal(int(os.Stdout.Fd()))

Break existing command signatures — treat flag/subcommand renames as breaking changes.
Require interactive input in CI/CD environments — always provide non-interactive fallbacks via flags or env vars.
Hardcode paths or platform-specific logic — use os.homedir() / os.UserHomeDir() / Path.home() instead.
Ship without shell completions — all three frameworks above have built-in completion generation.

Output Templates

When implementing CLI features, provide:

Command structure (main entry point, subcommands)
Configuration handling (files, env vars, flags)
Core implementation with error handling
Shell completion scripts if applicable
Brief explanation of UX decisions

Knowledge Reference

CLI frameworks (commander, yargs, oclif, click, typer, argparse, cobra, viper), terminal UI (chalk, inquirer, rich, bubbletea), testing (snapshot testing, E2E), distribution (npm, pip, homebrew, releases), performance optimization

Documentation

More skills from Jeffallan/claude-skills

Aangular-architectGenerates Angular 17+ standalone components, configures advanced routing with lazy loading and guards, implements NgRx state management, applies RxJS patterns, and optimizes bundle performance. Use when building Angular 17+ applications with standalone components or signals, setting up NgRx stores, establishing RxJS reactive patterns, performance tuning, or writing Angular tests for enterprise apps.
Aapi-designerUse when designing REST or GraphQL APIs, creating OpenAPI specifications, or planning API architecture. Invoke for resource modeling, versioning strategies, pagination patterns, error handling standards.
Aarchitecture-designerUse when designing new high-level system architecture, reviewing existing designs, or making architectural decisions. Invoke to create architecture diagrams, write Architecture Decision Records (ADRs), evaluate technology trade-offs, design component interactions, and plan for scalability. Use for system design, architecture review, microservices structuring, ADR authoring, scalability planning, and infrastructure pattern selection — distinct from code-level design patterns or database-only design tasks.
Aatlassian-mcpIntegrates with Atlassian products to manage project tracking and documentation via MCP protocol. Use when querying Jira issues with JQL filters, creating and updating tickets with custom fields, searching or editing Confluence pages with CQL, managing sprints and backlogs, setting up MCP server authentication, syncing documentation, or debugging Atlassian API integrations.
Achaos-engineerDesigns chaos experiments, creates failure injection frameworks, and facilitates game day exercises for distributed systems — producing runbooks, experiment manifests, rollback procedures, and post-mortem templates. Use when designing chaos experiments, implementing failure injection frameworks, or conducting game day exercises. Invoke for chaos experiments, resilience testing, blast radius control, game days, antifragile systems, fault injection, Chaos Monkey, Litmus Chaos.
Acloud-architectDesigns cloud architectures, creates migration plans, generates cost optimization recommendations, and produces disaster recovery strategies across AWS, Azure, and GCP. Use when designing cloud architectures, planning migrations, or optimizing multi-cloud deployments. Invoke for Well-Architected Framework, cost optimization, disaster recovery, landing zones, security architecture, serverless design.
Acode-documenterGenerates, formats, and validates technical documentation — including docstrings, OpenAPI/Swagger specs, JSDoc annotations, doc portals, and user guides. Use when adding docstrings to functions or classes, creating API documentation, building documentation sites, or writing tutorials and user guides. Invoke for OpenAPI/Swagger specs, JSDoc, doc portals, getting started guides.
Acode-reviewerAnalyzes code diffs and files to identify bugs, security vulnerabilities (SQL injection, XSS, insecure deserialization), code smells, N+1 queries, naming issues, and architectural concerns, then produces a structured review report with prioritized, actionable feedback. Use when reviewing pull requests, conducting code quality audits, identifying refactoring opportunities, or checking for security issues. Invoke for PR reviews, code quality checks, refactoring suggestions, review code, code quality. Complements specialized skills (security-reviewer, test-master) by providing broad-scope review across correctness, performance, maintainability, and test coverage in a single pass.
Acpp-proWrites, optimizes, and debugs C++ applications using modern C++20/23 features, template metaprogramming, and high-performance systems techniques. Use when building or refactoring C++ code requiring concepts, ranges, coroutines, SIMD optimization, or careful memory management — or when addressing performance bottlenecks, concurrency issues, and build system configuration with CMake.
Acsharp-developerUse when building C# applications with .NET 8+, ASP.NET Core APIs, or Blazor web apps. Builds REST APIs using minimal or controller-based routing, configures database access with Entity Framework Core, implements async patterns and cancellation, structures applications with CQRS via MediatR, and scaffolds Blazor components with state management. Invoke for C#, .NET, ASP.NET Core, Blazor, Entity Framework, EF Core, Minimal API, MAUI, SignalR.
Adatabase-optimizerOptimizes database queries and improves performance across PostgreSQL and MySQL systems. Use when investigating slow queries, analyzing execution plans, or optimizing database performance. Invoke for index design, query rewrites, configuration tuning, partitioning strategies, lock contention resolution.
Adebugging-wizardParses error messages, traces execution flow through stack traces, correlates log entries to identify failure points, and applies systematic hypothesis-driven methodology to isolate and resolve bugs. Use when investigating errors, analyzing stack traces, finding root causes of unexpected behavior, troubleshooting crashes, or performing log analysis, error investigation, or root cause analysis.

All agent skills → · MCP servers