marrow-mcp

Give your AI agents read-only access to your own Apple Health data.

Marrow is a free iOS app that pulls 174 Apple Health metrics, your food diary and your workouts into one place. This repo is its self-hosted companion server: one Python file, standard library only, that keeps a SQLite mirror of your data on hardware you own and serves it over the Model Context Protocol so agents can query it 24/7, phone in your pocket.

Nothing here talks to a cloud. Data flows phone → your machine, full stop.

Run it

python3 marrow_server.py                      # prints a pairing URL
python3 marrow_server.py --port 8800 --data ./data

or

docker compose up -d

Open the pairing URL on any screen, then in Marrow: Server → Pair with a server → scan. From then on the app's background pushes keep the mirror current with the app closed.

Connect an agent

The server speaks MCP over Streamable HTTP (JSON-RPC 2.0, protocol version 2025-06-18), authenticated with a bearer token it generates on first run and prints alongside the pairing link.

Claude Code

claude mcp add --transport http marrow \
  http://<server-ip>:8800/mcp \
  --header "Authorization: Bearer <mcp token>"

Claude Desktop, one click

Download marrow.mcpb, double-click it, and Claude Desktop installs the extension and asks for the URL and token. No terminal involved. (The bundle is a tiny zero-dependency bridge in mcpb/; it forwards Claude's stdio to your Marrow URL and nothing else.)

Claude Desktop (manual), Cursor, or anything using an mcp.json

{
  "mcpServers": {
    "marrow": {
      "type": "http",
      "url": "http://<server-ip>:8800/mcp",
      "headers": { "Authorization": "Bearer <mcp token>" }
    }
  }
}

Check it by hand

curl -s http://<server-ip>:8800/mcp \
  -H "Authorization: Bearer <mcp token>" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Tools

All read-only. Nothing an agent can call writes to your health record.

Then ask your agent things like "how did my sleep change once I started training in the mornings?" and let it go and look.

The other three ways in

This server is one of four, and you do not need it to give agents access:

1. On-device MCP. Marrow runs the same MCP surface on the iPhone itself at http://<phone-ip>:21212/mcp, answering while the app is running. Richest data, zero extra hardware.
2. This server. Always-on mirror on your own box.
3. Relay gateway. Serves the mirror when the phone is asleep.
4. Manual files. CSV, JSON and GPX out of the share sheet, plus scheduled webhook pushes to any URL (Home Assistant, n8n, your own endpoint).

All four are in the free tier. Setup for all of them: https://skeletonarmy.tech/mcp.

Security

• Both servers are built for a LAN or a tailnet. Do not port-forward this to the open internet. If you need it remotely, front it with tailscale serve, Caddy, or an equivalent so the transport is HTTPS and the device is authenticated before the bearer token is ever presented.
• Two separate tokens live in --data: .app-token for the phone's pushes and .mcp-token for agents. Rotating one does not disturb the other.
• Ingest is idempotent and UUID-keyed, so a replayed batch cannot double-count.

Status

Marrow is in TestFlight beta (0.2.0, build 85), iOS 17+, and requires Apple Health. Ask for an invite.

The iOS app is closed source; this server is not, because you should be able to read anything you are asked to run on your own hardware.

Registry

Listed in the official MCP registry as tech.skeletonarmy/marrow, verified by DNS on skeletonarmy.tech.

mcp-name: tech.skeletonarmy/marrow

Help and policies

• Agent setup guide, the full client-by-client walkthrough
• Support and troubleshooting, or email support@skeletonarmy.tech
• Privacy policy. Short version: your health data stays on your device, this server runs on hardware you own, and nothing here reports to us.
• Terms of use

Licence

MIT. See LICENSE.