Building an AI Agent with Ruby and Rails from Scratch — What No One Tells You

Ruby developers building AI agents in Rails face numerous challenges beyond simple implementation. Context windows require careful management, as LLMs can't process entire PDFs directly. The MCP server provides tool infrastructure, but doesn't handle RAG functionality, requiring separate embedding and retrieval systems. Developers must choose models supporting tool calls, structure Rails code properly, handle SDK quirks, and implement cycling message patterns to maintain context within token limits.