Read it in order
The sidebar is the order. It crosses section boundaries, and every page has a prev/next pager at the bottom, so you can start at the first page and finish at the last without ever choosing what to read next.
You can jump. Section 6 is a reference and stands alone. But sections 1 through 5 are a sequence — each one opens by breaking something the previous one assumed, and that only lands if you were there when the assumption was made.
| If you are… | Start at |
|---|---|
| new to MCP entirely | What is MCP? — you are nearly there |
| curious what Claude Desktop is actually doing | 🔁 The Host |
| about to give an agent a dangerous tool | ✋ The Gate |
| watching an agent run out of room on big jobs | 👥 The Crew |
| worried something you connected can spend money | 💸 The Ledger |
| here for the war stories | The gotcha compendium |
Every project is real, live, and public
Nothing here is a worked example invented for a tutorial. All five were built, deployed, and are running right now.
An MCP server. Offers tools, waits.
the repo →An MCP host that owns the loop.
the repo →Approval gates, Postgres, evals, replay.
the repo →Sub-agents, one approval queue, cost measurement.
the repo →Sampling, a spend gate, a ledger.
the repo →The Run it all yourself page has the clone table, the prerequisites, and — explicitly — which commands spend money and which don't.
Every claim here has a number behind it
This is the property that makes the course worth your time, so it is worth saying plainly.
Every figure on this site came from a real run. 439k tokens. 0 of 36. 13/13
for $0.00. 2.01× becoming 1.08×. None of them are illustrative, rounded for
effect, or invented to make a point land harder.
The three-document convention
All five repos have the same three files, and the split is deliberate enough to steal:
| File | For | Answers |
|---|---|---|
README.md | Understanding | What is this? Why does it exist? |
BUILD_FROM_SCRATCH.md | Doing | Which commands, in what order, and what breaks? |
NEXT_STEP.md | Deciding | What's missing, and what should the next project be? |
The reason it works is that the three have genuinely different readers, and each stays useful because it is not trying to serve the other two.
Every BUILD_FROM_SCRATCH.md ends with an appendix titled "the N things that
actually broke." There are 40 of them across the five projects, and they
are collected — searchable, filterable, with the cause and the fix — in the
gotcha compendium.
Two conventions on this site
The section colour tells you where you are. Each of the six sections has one vivid accent, and it shows up on the headings, the active sidebar item, the rule at the top of the page, and the strokes in the diagrams. If the page is rose, you are in the Gate.
The diagrams are live. They are rendered in your browser from Mermaid source, not shipped as images, so they scroll inside their own box rather than blowing out the page. Most of them are lifted directly from the source READMEs where the per-node colours already carry meaning — red is failure, green is success, amber is the interesting bit.