MCPs work like magic. Internally we use them relentlessly inside Cursor, for Linear issues in particular. We decided to ship an MCP server with MCP Bundles mainly because it made sense for us to have it on our own product for testing, before we even provided it to our customers. We built it quickly and made choices-of-least-resistance so there may be better ways to do everything. This is why we wanted to share our experience, would love to hear your feedback.

So the headline is we decided to implement an MCP server, Model Context Protocol (MCP), in our Django application, built on top of our existing API endpoints, and get it working with Cursor and Claude 3.7.

Here's the thing about schemas: they're basically the contract your model learns from. Get them right, and your tools are easy to find, hard to break, and simple to fix when something goes wrong.

Get them wrong, and you'll spend way too much time debugging why the model keeps calling your tool incorrectly.

I spent two hours staring at Claude Desktop wondering why my MCP server wouldn't connect. The config looked perfect. The server ran fine standalone. But Claude showed no tools. The problem? A single trailing comma in my JSON config that Claude silently ignored.

This is everything I wish the docs had told me upfront.

New to MCP? Start with Introduction to MCP to understand what it is and how it works.

My first MCP server took three hours to get working because I made every possible mistake: no logging, broke stdio with print statements, forgot to restart Claude Desktop, and wondered why nothing worked. Your first one should take 30 minutes.

This is what actually works, with the debugging steps I wish I'd known upfront.

I watched Claude hallucinate API endpoints that didn't exist, confidently call made-up functions, and crash our systems with broken JSON. Then we implemented the Model Context Protocol (MCP), and our error rate dropped from 28% to under 3%.

This is what I wish someone had told me when I started.