new-provider

name	new-provider
description	Scaffold a new backend provider following project patterns (service + provider + tests)
disable-model-invocation	true

New Provider

Scaffold a new backend provider with all required files following project conventions.

Usage

/new-provider <name>

Examples:

• /new-provider scryfall
• /new-provider spellbook
• /new-provider seventeen_lands
• /new-provider edhrec

What Gets Created

Given /new-provider <name>:

1. Service client: src/mtg_mcp_server/services/<name>.py

import structlog
from mtg_mcp_server.services.base import DEFAULT_USER_AGENT, BaseClient, ServiceError

log = structlog.get_logger(service="<name>")

class <Name>Error(ServiceError): ...
class <Name>NotFoundError(<Name>Error): ...

class <Name>Client(BaseClient):
    """<Name> API client."""

    def __init__(
        self,
        base_url: str = "...",  # from Settings
        rate_limit_rps: float = ...,
        user_agent: str = DEFAULT_USER_AGENT,
    ) -> None:
        super().__init__(
            base_url=base_url,
            rate_limit_rps=rate_limit_rps,
            user_agent=user_agent,
        )

2. Provider sub-server: src/mtg_mcp_server/providers/<name>.py

from fastmcp import FastMCP
from fastmcp.server.lifespan import lifespan
from fastmcp.exceptions import ToolError

from mtg_mcp_server.config import Settings
from mtg_mcp_server.providers import TOOL_ANNOTATIONS
from mtg_mcp_server.services.<name> import <Name>Client

_client: <Name>Client | None = None

@lifespan
async def <name>_lifespan(server: FastMCP):
    global _client
    settings = Settings()
    client = <Name>Client(base_url=settings.<name>_base_url)
    async with client:
        _client = client
        yield {}
    _client = None

<name>_mcp = FastMCP("<DisplayName>", lifespan=<name>_lifespan)

def _get_client() -> <Name>Client:
    if _client is None:
        raise RuntimeError("<Name>Client not initialized — server lifespan not running")
    return _client

# Tools go here — each uses:
#   annotations=TOOL_ANNOTATIONS
#   client = _get_client()
#   ToolError for error responses

3. Test files

• tests/services/test_<name>.py — Service layer tests with respx mocks
• tests/providers/test_<name>_provider.py — Provider tests using FastMCP test client
• tests/fixtures/<name>/ — Directory for JSON fixtures (empty, user captures separately)

4. Pydantic models in src/mtg_mcp_server/types.py

Add response models for the service. Use model_validate(), not parse_obj().

Rules

• Follow TDD: write failing tests first, then implement
• Check docs/SERVICE_CONTRACTS.md for the service's API details
• Check docs/TOOL_DESIGN.md for the tools this provider should expose
• All tools are read-only and idempotent — annotate accordingly
• Use ToolError from fastmcp.exceptions for error responses
• Service clients via lifespan + module-level _client, never instantiate per call
• After scaffolding, remind the user to mount on the orchestrator in server.py