minimal mcp server

A single file MCP server backed by an in memory todo list. It touches all three MCP primitives (tools, resources, prompts) plus elicitation, in about 250 lines.

Architecture

The list lives in memory only. Nothing is written to disk, so every restart starts fresh with two seeded todos.

Three tools let Claude add a todo, mark one done, or delete one. Deleting is the only action that pauses mid call and asks you to confirm first, since it can't be undone; the other two just run.

Two resources expose the same data as read only content instead of actions. One returns the whole list as a markdown checklist. The other takes an id through a URI template and returns just that one item, converting the id from text to a number itself since URI segments always arrive as strings.

One prompt, plan_my_day, bundles the full list with an instruction asking Claude to pick the three most important undone items. Triggering it attaches the resource and sends the request in a single click instead of doing both by hand.

Related MCP server: Basic MCP Server

Run it

uv sync
uv run python smoke_test.py     # drives the server as a real client, 13 checks
uv run mcp dev todo_server.py   # opens the MCP Inspector

Connect it to a host

claude mcp add todos -- uv --directory "<path to this repo>" run python todo_server.py