Agent Skills: prompt-engineer

This skill should be used when the user asks to "create a prompt", "optimize a prompt", "improve this prompt", "engineer a prompt", "prompt engineering best practices", "make this prompt better", "recommend a model", "which model should I use", "best model for", "GPT vs Claude", "Opus vs Sonnet", "Haiku vs Sonnet", "analyze prompt quality", "fix my prompt", "prompt for Claude", "prompt for GPT", or needs help with prompt engineering techniques, model selection, or prompt optimization for any LLM (Claude Opus/Sonnet/Haiku 4.5, GPT 5.1/Codex, Gemini Pro 3.0).