MCP order tools

A local MCP server with account-scoped order tools, versioned proposals and application-owned approval.

Technical series · Architecture

Beginner setup and debugging

Run locally

Requires Python 3.12+. Uses the official MCP Python SDK 2.2.0.

python -m venv .venv
# Windows: .venv\Scripts\activate
# macOS/Linux: source .venv/bin/activate
python -m pip install -r requirements.txt
python -m unittest discover -s tests -v
python server.py

The server uses stdio: no browser page or listening network port. A compatible MCP host should launch the virtual environment's Python with the absolute path to server.py and the repository as its working directory. No API key is required.

Related MCP server: OrderOps MCP

Try the tools

1. get_order_status(order_id="ORDER-100") returns status and version, not customer data.

2. get_order_status(order_id="ORDER-200") returns the same safe not-found shape as an unknown ID.

3. prepare_address_change validates and returns a version-bound proposal.

4. apply_approved_change returns approval_required until the trusted application approves it.

There is deliberately no approve tool. The handler tests demonstrate the trusted review path, repeated application and stale proposals. The standalone MCP server does not provide a human approval UI, so its write tool cannot succeed through model calls alone.

Design and limits

• Account context is fixed to a fictional demo account at launch; tool arguments cannot choose it.

• Every handler checks ownership again, including applying a stored proposal.

• Proposals pin the normalized address and version; changing either needs a new review.

• Completed proposal IDs return the existing local outcome.

This in-memory, single-process exercise has no production authentication, concurrent transaction store, provider API or persistent audit trail. Local deduplication does not make a remote provider write idempotent. A real deployment needs authenticated context, durable operations and reconciliation for uncertain external results, as described in the guide and diagram. Do not expose this teaching server as an authenticated production service.

Further reading

• Official MCP Python SDK

• MCP architecture

Provenance and license

Original educational examples by Abdul Rehman. All scenarios are fictional; no customer records, credentials or private product source are included. Released under the MIT license.