If you're building with AI in 2026, sooner or later you run into the same question: how do you connect models to real systems without turning your architecture into a pile of one-off glue?
That's the problem space behind MCP. And it's why I'm writing The Definitive Guide to Building Model Context Protocol (MCP) Servers.
You can read the draft here: mcp.johnaaronnelson.com
Why write a book on MCP now?
There's a lot of energy around MCP, but not much material yet that treats it like an engineering discipline instead of a novelty. Most of what's out there falls into one of a few buckets:
- quick starts that get you to a demo
- protocol overviews that explain the shape of MCP but not the tradeoffs
- client-specific examples that don't generalize well
- scattered discussions about security, auth, and deployment
That's useful, but it leaves a gap. The hard part isn't proving that an MCP server can work. The hard part is deciding what should be an MCP server at all, how to design the interface well, and how to operate it safely once it matters.
That's the gap this book is meant to cover.
Who this book is for
This book is for builders and operators who need practical answers, including:
- engineers designing AI-facing interfaces to existing systems
- consultants helping companies adopt MCP without creating long-term messes
- product teams turning internal workflows into model-usable capabilities
- technical leaders evaluating where MCP belongs in their stack
It's not aimed at hype. It's aimed at people shipping.
What the book covers
The draft currently spans architecture, implementation, integration patterns, security, deployment, and operations. The goal is to move from first principles all the way to production reality.
A few themes run through the whole manuscript:
- good MCP servers are product surfaces, not just protocol wrappers
- the model-facing interface matters as much as the backend code
- security, cost, and operability have to be first-draft concerns
- plenty of projects should not become MCP servers
If that framing resonates, this book will probably be useful to you.
Read the draft
I've published the working draft at mcp.johnaaronnelson.com. It's a living manuscript, and I'm continuing to expand the thinner chapters into a more complete reference over time.
If you want the short version, start here too:
More book-related writing will show up here as the manuscript develops.