Chat-based agents are augmented LLM interfaces with access to a list of predefined tools. RubyLLM Agents are reusable AI assistants implemented as models with their configuration, runtime context, and prompt conventions. Let's see how we can start implementing custom OpenAI chat agents with access to SERP tools with the help of the RubyLLM gem.

💡 Note the difference between fully autonomous agents like Claude Code or Codex, and chat-based agents that still react to user input. This post is about the latter.

Simple chats vs agents

RubyLLM is a Ruby gem and an AI interface for GPT, Claude, and Gemini to give us an easy way to run LLM chat inside a Ruby application. It allows us to avoid writing JSON and lets us work with AI using beautiful Ruby DSL.

A regular RubyLLM chat is a conversation. A user sends a message, the model responds, and the exchange continues back and forth. It works but it's limited to what the model can do.…