Marrow

Marrow Health MCP server (marrow-mcp)

Let your AI agents read your own Apple Health data.

Marrow is a free iOS app that tracks 178 health data series - 172 Apple Health types plus its own meal diary and set-by-set weightlifting log. 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.

[An agent querying Marrow over MCP: sleep and workout data answered from the phone]

Run it

pip install "marrow-mcp[qr]"                  # [qr] adds segno, which draws the pairing QRmarrow-server --port 8800 --data ./data       # prints a pairing URL

Without [qr] the pairing page shows the pairing JSON instead of a code.

or from a clone

python3 marrow_server.py                      # prints a pairing URLpython3 marrow_server.py --port 8800 --data ./data

or with Docker

docker compose up -d

Open the pairing URL on any screen, then in Marrow: Export, Server MCP, Pair with a server, and scan. From then on the app's background pushes keep the mirror current with the app closed. The app pairs over plain http only on your own networks (a private or tailnet IPv4 address, a .local or .ts.net name, a short LAN name). A public address needs https (--url https://...).

Upgrading to 0.3.0

Stop the old server and start the new one on the same --data directory. An existing mirror.sqlite gains the new columns on first start, and the tokens in --data carry over, so the phone stays paired. Sets logged by Marrow 1.4 carry a set_type (work, warmup, failure or drop). Warm-ups are still listed but no longer count toward volume or records, and rows mirrored before the upgrade read as work sets.

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

Thirteen tools, all of them reads. The server also carries write tools (log a meal, a workout and so on), but it lists them only after a phone registers it for write-back, and today only Marrow Connect does that. A self-hosted server paired from the app serves the thirteen reads and nothing an agent can call writes to your health record.

Four of them answer in the app's own terms, scored against your own trailing normal with the same math the app's Home page uses (the day itself excluded), so an agent starts from a read that is already true for you instead of judging a number against the population:

The nine raw reads:

Every read takes days back from the phone's today, or from and to on the phone's calendar. metric_samples pages with before (the start of the last record you have). Tools with an output schema also answer with structuredContent.

Four prompts come with the server (how_am_i_doing, weekly_review, doctor_prep, log_from_text) and four resources (marrow://today, marrow://metrics, marrow://targets, marrow://quality), for the clients that show them.

Metric keys: list_metrics shows Apple's short names (active_energy_burned), and the tools also accept the app's own keys (active_energy, heart_rate_variability), so an agent moved over from the phone keeps its vocabulary.

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

Kits, recipes and the Claude Code plugin

• kits/: copy-and-paste setup for Claude Code, Claude Desktop, Cursor, OpenClaw and Hermes Agent.
• recipes/: receivers for Marrow's Automations (the app POSTs your data to any URL on a schedule, with the app closed): Home Assistant, n8n, Google Sheets through Apps Script, InfluxDB.
• Built with Marrow: complete projects people run on these connections, starting with Body Ops, a Grafana dashboard for every kind of data Marrow sends. Submit yours there.
• The Claude Code plugin: /plugin marketplace add MarrowHealth/marrow-mcp then /plugin install marrow-health@marrow. It adds the Marrow Connect server and four commands (/marrow-health:how-am-i-doing, weekly-review, doctor-prep, log) plus a skill that knows which tool answers what.

Why not the built-in Claude or ChatGPT connector?

Both Claude (Pro/Max, US) and ChatGPT now read Apple Health natively. Use them if that is all you need. They stop where this server starts:

OpenClaw / Hermes / any agent on a home machine. Point the agent's MCP config at the server URL with the bearer token, exactly as in the mcp.json block above. Reach it from outside the LAN with tailscale serve --bg --https=8800 http://127.0.0.1:8800 and use the tailnet URL.

The other ways in

This server is one of the doors on Marrow's Export tab, and you do not need it to give agents access:

1. Local MCP. Marrow runs an MCP server on the iPhone itself at http://<phone-ip>:21212/mcp, answering while the app is running. Seven of the raw reads above, zero extra hardware.
2. Server MCP. This package: an always-on mirror on your own box.
3. Automated. Scheduled pushes to any URL (Home Assistant, n8n, your own endpoint).
4. Manual. CSV, JSON and GPX files out of the share sheet.

All four are in the free tier. Setup for all of them: https://marrowhealthapp.com/guides.

Marrow Connect is the hosted Pro path: Marrow runs the mirror, and ChatGPT, Claude or Gemini read it with the phone asleep and nothing to run. It is the only door that can log for you, once you turn on Allow AI write in the app. https://marrowhealthapp.com/connect

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 on the App Store, iOS 17+, and requires Apple Health. Get it on the App Store.

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 [email protected]
• 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.