What we learned shipping AI agents to production
Agents are fun in a demo and humbling in production. Here are the guardrails that made ours reliable enough to trust.
Agents are fun in a demo and humbling in production. Here are the guardrails that made ours reliable enough to trust.
Function calling, agents, and MCP all rest on the same thing: tools an LLM can invoke. But a tool built for a non-deterministic, fallible caller needs different design than one built for code. A deep-dive on what makes a tool reliable for an LLM — naming, scope, validation, error messages it can recover from, and the safety that can't live in the model.
Put the pieces together — the no-Redis Solid stack, Kamal, pgvector, and the hard-won disciplines of building with LLMs — and a coherent picture emerges: Rails is an outstanding host for AI-native applications, precisely because it lets a small team build and run both the app and its AI features. A synthesis of where the stack stands.
The most reliable AI systems in production aren't fully autonomous — they keep a human at the decision points that matter. But 'human in the loop' is easy to do badly: rubber-stamp approvals, alert fatigue, humans blamed for the model's mistakes. A deep-dive on designing the human-AI division of labour so both do what they're good at.
I've championed pgvector as the sensible default for vector search. After running it in production, here's what the introductory tutorials leave out: index choice and its trade-offs, the recall-versus-speed dial, keeping embeddings in sync, and the operational realities that only show up at scale.
There are three ways to make an LLM do what your application needs — prompting, retrieval, and fine-tuning — and teams routinely reach for the wrong one. They solve different problems, and the costs differ enormously. A trend post on what each is actually for, and a decision order that saves you from over-engineering.
Once your semantic search outgrows a toy dataset, the question arrives: stay with pgvector in Postgres, or move to a dedicated vector database like Pinecone, Qdrant, or Weaviate? A deep-dive on what actually changes at scale, what you give up by leaving Postgres, and how to decide without over-engineering.
Open-weight models like Llama 2 and Mistral mean you can now run a capable LLM on your own infrastructure instead of calling someone's API. A look at why you'd want to — privacy, cost, control — what it actually costs you in ops, and the honest question of whether you should.
Function calling lets an LLM ask your code to run a function and use the result — turning a model that can only talk into one that can look things up and act. A deep-dive on how it actually works, why it's just structured output with a loop around it, and why you stay firmly in control of what actually runs.