marrow-mcp
Give your AI agents read-only access to 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.
Run it
python3 marrow_server.py
python3 marrow_server.py --port 8800 --data ./data
or
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"}'
All read-only. Nothing an agent can call writes to your health record.
| Tool | Returns |
|---|
health_summary | Recent days across activity, heart, sleep and nutrition |
list_metrics | Every metric in the mirror, with units and coverage |
metric_daily | Daily values for any metric, up to 400 days |
metric_samples | Raw records with timestamps and source devices |
workouts | Workouts, including set-by-set strength detail |
nutrition_log | The meal diary: every logged food with full nutrient detail, by day |
strength_log | Every lifting set with estimated 1RM, per-exercise progression, and volume per muscle group |
Then ask your agent things like "how did my sleep change once I started
training in the mornings?" and let it go and look.
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:
| Claude / ChatGPT connector | Marrow + this server |
|---|
| Where it works | The iOS app only | Claude Code, Claude Desktop, Cursor, OpenClaw, Hermes, any MCP client, on any machine |
| When it works | While you are in the chat on the phone | 24/7, phone in your pocket, from your own box |
| What the model sees | Raw HealthKit numbers | Daily values reconciled against Apple's own totals, meal diary, set-by-set lifts |
| Where the data lives | Their cloud, per conversation | SQLite on hardware you own |
| Cost | Subscription | Free, MIT |
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 three ways in
This server is one of four, and you do not need it to give agents access:
- 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.
- This server. Always-on mirror on your own box.
- Relay gateway. Serves the mirror when the phone is asleep.
- 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
Licence
MIT. See LICENSE.