Rails Agents (gem: rails-agent-stack) is the simplest way to build AI agents in Ruby on Rails. Define an LLM agent as a plain Ruby class, attach your app code as tools, add skills like web search or spreadsheets, and call .run — minutes to production, not days of framework setup. Built for developers searching for Rails AI agents, Ruby LLM agents, OpenAI / Anthropic / Claude / GPT tool-calling agents, OpenRouter and Grok (xAI) integrations, agentic workflows, RAG helpers, and a lighter alternative to RubyLLM, LangChain, or rolling your own multi-turn tool loop. One mental model: RailsAgents::Agent. No dashboards, no cloud lock-in, no agent lifecycle UI — just provider, model, description, tools, and skills.