mcp-nutrition-db

mcp-nutrition-db is a private MCP service that lets ChatGPT record, correct, and query meal nutrition and nutrition goals. ChatGPT interprets meal photos and conversation context; this service owns the durable, auditable data.

The production service is intended to run on the NixOS host kage. It listens only on loopback and is reached from ChatGPT through OpenAI Secure MCP Tunnel, so it does not require an nginx route or a public MCP endpoint.

Project documents

• System design defines the product boundary, MCP tools, data model, security model, and NixOS deployment.

• Implementation plan is the source of truth for phases, acceptance criteria, progress, and deferred work.

• Local testing explains direct Codex attachment and the temporary Secure MCP Tunnel workflow for ChatGPT Web.

The implementation plan should be updated in the same commit as meaningful implementation milestones. Design changes should be recorded in the decision log before or alongside the code that depends on them.

Related MCP server: Nutrition MCP Server

Current status

The local MVP implements the SQLite schema and all eight MCP tools. Repository, schema, calendar, MCP process, Streamable HTTP, package, and NixOS evaluation checks pass; see the implementation plan for the exact verified state.

Development

Enter the pinned environment and run the checks:

nix develop
PYTHONPATH=src ruff format --check src tests
PYTHONPATH=src ruff check src tests
PYTHONPATH=src mypy src
PYTHONPATH=src pytest

Run a loopback development server with disposable state:

nix run . -- serve --database /tmp/mcp-nutrition-db.sqlite3

The MCP endpoint is http://127.0.0.1:8787/mcp; readiness is available at http://127.0.0.1:8787/healthz. The server refuses a non-loopback HTTP bind by default. See local testing to attach a new Codex session or run the pinned tunnel client for ChatGPT Web.