Ship your first real MCP server

Another toy demo. Still not one real agent actually calls.

BeginnerRead 6 minDoing: about an hour, with your editor and Claude Desktop both open7 steps

▶ Start

What you'll have at the end

A local MCP server with one working tool, confirmed calling and answering correctly inside Claude Desktop

Before you start

You need

Claude Desktop installed and signed in, and comfort writing and running a small script in one language with its package manager already set up.

Not covered

This does not cover wiring more than one tool, adding resources or prompts, moving the server off your own machine, or working out why a visible tool still gets ignored by name: only the first tool, run locally, confirmed with one real answer.

Leans on

Write a tool with a real answer to give

Pick a live fact to check
Write the function and its schema
Run the server on its own first

Wire it into your host

Tell your host where the tool lives
Restart fully, then check it shows up

Prove it actually works

Ask the real question, watch the call
Confirm the number against the source

Where to go next

Catch a broken MCP tool with Inspector

for when discovery or the call itself fails and you need to see the raw protocol exchange instead of guessing from the host's own behavior.

Rename an MCP tool the model ignores

for when the tool shows up in the list and the host still never reaches for it: that is a naming problem, separate from getting it wired in at all.

Checked 15 Aug 2026

Part of the MCP Servers Implementation cookbook