Rebuild the docs around tested examples; shrink README.v2.md to a pitch (#2978)

docs/tutorial/index.md

@@ -0,0 +1,51 @@
+# Tutorial - User Guide
+
+This tutorial shows you how to use the MCP Python SDK, step by step.
+
+Each section gradually builds on the previous ones, but it's written so you can go straight to any specific section to solve a specific problem. It also works as a future reference: you can come back to exactly the part you need.
+
+## Run the code
+
+All the code blocks can be copied and used directly: they are complete, working files.
+
+To follow along, paste a block into a `server.py` and open it in the MCP Inspector:
+
+```console
+uv run mcp dev server.py
+```
+
+It is **HIGHLY encouraged** that you write (or copy) the code, edit it, and run it locally. Using it in your own editor is what really shows you the point: how little you write, the autocompletion, the type checks catching mistakes before you run anything.
+
+## You will not be guessing
+
+Every example in this tutorial is a complete file under [`docs_src/`](https://github.com/modelcontextprotocol/python-sdk/tree/main/docs_src) in the SDK's own repository, and every one of them is exercised by the SDK's test suite through an **in-memory client**:
+
+```python
+import pytest
+from mcp import Client
+
+from server import mcp
+
+
+@pytest.mark.anyio
+async def test_add() -> None:
+    async with Client(mcp) as client:
+        result = await client.call_tool("add", {"a": 1, "b": 2})
+        assert result.structured_content == {"result": 3}
+```
+
+No subprocess, no port, no transport. `Client(mcp)` connects to the server object directly.
+
+If a change to the SDK breaks an example on one of these pages, CI goes red before the page does. The code you read here is the code that runs.
+
+You'll use this yourself in the [Testing](testing.md) chapter; it's how you test your own servers, too.
+
+## Install the SDK
+
+If you haven't yet, [install the SDK](../installation.md) first.
+
+## Advanced User Guide
+
+There is also an **Advanced User Guide** you can read after this one.
+
+It builds on this tutorial, uses the same concepts, and teaches you the extra things: the low-level `Server`, middleware, authorization, the 2026-07-28 protocol negotiation. But you should read this first: everything in the Advanced guide assumes you know the basics.