README.md

Week 1 — Hobby Track: mtg.card_lookup

This is a minimal MCP server in Python that exposes two tools:

• health.check — returns version, current time, and a simple learning streak counter stored in streak.json.
• mtg.card_lookup — Day 1 returns a fake response (proves wiring). On Day 2, switch to Scryfall API.

Quick start

python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate
pip install --upgrade pip
pip install mcp uvloop (optional on Windows)

# Run the server over stdio (default)
python src/server.py

If your client expects a command, point it at python src/server.py.

Files

/mcp-mtg-week1
  ├─ src/
  │   ├─ server.py            # MCP server entry point
  │   └─ tools/
  │       ├─ __init__.py
  │       └─ card_lookup.py   # tool implementation (fake → real)
  ├─ logs/
  └─ streak.json              # created on first run

Day 2 switch (Scryfall)

• Replace the fake result in card_lookup.lookup() with a real HTTP call to Scryfall's named endpoint:
  • https://api.scryfall.com/cards/named?fuzzy=<name>
• Keep the same return schema.

---

src/server.py

import asyncio import json import logging from datetime import datetime, timezone from pathlib import Path

try: import uvloop # type: ignore asyncio.set_event_loop_policy(uvloop.EventLoopPolicy()) except Exception: pass

from mcp.server import Server from mcp.types import TextContent

from tools.card_lookup import lookup as mtg_lookup, FakeCardLookupError

APP_VERSION = "0.1.0" BASE_DIR = Path(file).resolve().parent.parent LOG_DIR = BASE_DIR / "logs" LOG_DIR.mkdir(parents=True, exist_ok=True) STREAK_FILE = BASE_DIR / "streak.json"

logging.basicConfig( level=logging.INFO, format="%(asctime)s | %(levelname)s | %(name)s | %(message)s", handlers=[ logging.FileHandler(LOG_DIR / "week1.log"), logging.StreamHandler() ] ) logger = logging.getLogger("mcp-mtg-week1")

server = Server("mcp-mtg-week1")

def _load_streak() -> int: if STREAK_FILE.exists(): try: data = json.loads(STREAK_FILE.read_text()) return int(data.get("streak_days", 0)) except Exception: return 0 return 0

def _save_streak(days: int) -> None: STREAK_FILE.write_text(json.dumps({"streak_days": days}, indent=2))

@server.tool() async def health_check() -> dict: """Return server version, current time (UTC), and learning streak days.""" now = datetime.now(timezone.utc).isoformat() days = _load_streak() # Nudge the counter once per run (simple Day-1 behavior) _save_streak(days + 1) payload = {"version": APP_VERSION, "now": now, "streak_days": days + 1} logger.info("health.check -> %s", payload) return payload

@server.tool() async def mtg_card_lookup(name: str) -> dict: """Fuzzy-lookup a Magic card by name. Day-1: fake response to prove wiring.""" start = datetime.now(timezone.utc) try: result = await mtg_lookup(name=name) logger.info("mtg.card_lookup name=%r -> ok", name) return result except FakeCardLookupError as e: logger.warning("mtg.card_lookup name=%r -> not_found: %s", name, e) return { "error": "not_found", "message": str(e), "suggestion": "Try a different name or check spelling." } finally: end = datetime.now(timezone.utc) elapsed_ms = int((end - start).total_seconds() * 1000) logger.info("mtg.card_lookup elapsed_ms=%d", elapsed_ms)

async def amain() -> None: # Default transport: stdio await server.run_stdio_async()

if name == "main": asyncio.run(amain())

src/tools/init.py

Intentionally empty; makes tools a package.

src/tools/card_lookup.py

import asyncio from dataclasses import dataclass

@dataclass class FakeCardLookupError(Exception): query: str def str(self) -> str: return f"No fake match for query: {self.query}"

async def lookup(name: str) -> dict: """ Day-1 fake implementation. - Accepts any name containing 'atraxa' (case-insensitive) and returns a fixed object. - Otherwise raises FakeCardLookupError so the server can return a friendly error.

Day-2: replace this with a real HTTP call to Scryfall's `named?fuzzy=...` endpoint.
"""
if not isinstance(name, str) or not name.strip():
    raise FakeCardLookupError(query=name)

await asyncio.sleep(0.05)  # small delay to exercise logging

if "atraxa" in name.lower():
    return {
        "name": "Atraxa, Grand Unifier",
        "type_line": "Legendary Creature — Phyrexian Angel",
        "oracle_text": (
            "Flying, vigilance, deathtouch, lifelink — When Atraxa, Grand Unifier "
            "enters the battlefield, reveal the top ten cards of your library. For each "
            "card type, you may put a card of that type from among them into your hand."
        ),
        "mana_value": 7,
        "image_small": "https://cards.scryfall.io/small/front/5/9/59....jpg",
        "rulings_uri": "https://api.scryfall.com/cards/xxxx/rulings"
    }

raise FakeCardLookupError(query=name)