Cronometer MCP Server

cronometer-mcp

An MCP (Model Context Protocol) server that provides access to your Cronometer nutrition data. Pull detailed food logs, daily macro/micro summaries, manage diary entries, fasting, biometrics, and recurring foods — all from Claude, Cursor, or any MCP-compatible client.

Requires a Cronometer Gold account (or any paid tier that supports web login).

Features

• Food log — individual food entries with full macro and micronutrient breakdown
• Daily nutrition — daily calorie, protein, carb, fat, and fiber totals
• Micronutrients — detailed vitamin/mineral breakdown with period averages
• Diary management — add/remove food entries, copy entire days, mark days complete
• Recurring foods — create, list, and delete repeat items that auto-log on selected days
• Macro targets — read/write daily targets, create templates, set weekly schedules
• Fasting — view history and stats, cancel or delete fasts
• Biometrics — log and remove weight, blood glucose, heart rate, body fat
• Raw CSV export — servings, daily summary, exercises, biometrics, or notes
• Sync to disk — download JSON exports and generate a markdown food log

Quick Start

1. Install

pip install cronometer-mcp

Or install from source:

git clone https://github.com/cphoskins/cronometer-mcp.git
cd cronometer-mcp
pip install -e .

2. Set credentials

export CRONOMETER_USERNAME="your@email.com"
export CRONOMETER_PASSWORD="your-password"

Or add them to a .env file in your project root (if your MCP client supports it).

3. Configure your MCP client

Claude Code (.mcp.json)

{
  "mcpServers": {
    "cronometer": {
      "command": "cronometer-mcp",
      "env": {
        "CRONOMETER_USERNAME": "your@email.com",
        "CRONOMETER_PASSWORD": "your-password"
      }
    }
  }
}

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "cronometer": {
      "command": "cronometer-mcp",
      "env": {
        "CRONOMETER_USERNAME": "your@email.com",
        "CRONOMETER_PASSWORD": "your-password"
      }
    }
  }
}

If you installed from source with pip install -e ., you can also use the full Python path:

{
  "command": "/path/to/venv/bin/python",
  "args": ["-m", "cronometer_mcp.server"]
}

Available Tools

Food Log & Nutrition

Food Search & Diary Management

Recurring Foods (Repeat Items)

Macro Targets & Templates

Fasting

Biometrics

Sync

Tool Parameters

All date parameters use YYYY-MM-DD format. Most tools default to today or the last 7 days when dates are omitted.

Key parameter patterns:

• diary_group — a diary group name (case-insensitive) or a 0-based index. Cronometer Gold gives every account 8 diary group slots and lets you rename and enable them freely, so the names are account-specific and are not always Breakfast/Lunch/Dinner/Snacks. Call list_diary_groups to see yours. On an untouched account the four standard meals are indices 1–4 (index 0 is a slot that ships disabled). Unknown names, disabled groups, and out-of-range indices are rejected rather than silently defaulting — Cronometer itself accepts a bad index without complaint and the entry becomes unreachable.
• days_of_week — "all", "weekdays", "weekends", or comma-separated day numbers (0=Sun through 6=Sat)
• measure_id — pass 0 to use the universal gram-based measure (works for all food sources)
• target_date — pass "all" on get_macro_targets to get the full weekly schedule

Sync Output

The sync_cronometer tool saves files to ~/.local/share/cronometer-mcp/ by default. Override with the CRONOMETER_DATA_DIR environment variable:

export CRONOMETER_DATA_DIR="/path/to/your/project/data/cronometer"

Output files:

• exports/servings_{start}_{end}.json
• exports/daily_summary_{start}_{end}.json
• exports/servings_latest.json
• exports/daily_summary_latest.json
• food-log.md

How It Works

Cronometer does not have a public API for individual users. This server uses the same GWT-RPC (Google Web Toolkit Remote Procedure Call) protocol that the Cronometer web app uses internally:

1. Fetches the login page to get an anti-CSRF token
2. POSTs credentials to authenticate
3. Calls GWT-RPC authenticate to get a user ID
4. Calls GWT-RPC generateAuthorizationToken for short-lived export tokens
5. Downloads CSV exports using the token
6. Calls GWT-RPC methods directly for diary edits, fasting, biometrics, macro targets, and repeat items

Session cookies are persisted to ~/.local/share/cronometer-mcp/.session_cookies so that subsequent invocations reuse the session without re-authenticating (Cronometer has aggressive login rate limiting).

GWT Magic Values

The GWT protocol uses a permutation hash and header value that are baked into each Cronometer web deploy. These values are hardcoded in the client and may break when Cronometer pushes a new build.

Current values (as of February 2026):

• Permutation: 7B121DC5483BF272B1BC1916DA9FA963
• Header: 2D6A926E3729946302DC68073CB0D550

If authentication starts failing with GWT errors, these values likely need updating. You can find the current values by:

1. Opening Cronometer in your browser
2. Going to Developer Tools → Network tab
3. Looking for requests to cronometer.com/cronometer/app
4. Checking the x-gwt-permutation header and the payload structure

You can override them via the CronometerClient constructor:

from cronometer_mcp import CronometerClient

client = CronometerClient(
    gwt_permutation="NEW_PERMUTATION_HASH",
    gwt_header="NEW_HEADER_VALUE",
)

Python API

You can also use the client directly in Python:

from datetime import date, timedelta
from cronometer_mcp import CronometerClient

client = CronometerClient()  # reads from env vars

# Get today's food log
foods = client.get_food_log()

# Get last 7 days of daily summaries
start = date.today() - timedelta(days=7)
summaries = client.get_daily_summary(start)

# Raw CSV export
csv_text = client.export_raw("exercises", start, date.today())

# Copy a day's diary entries
client.copy_day(date(2026, 3, 1), date(2026, 3, 8))

# Add a recurring food entry (every weekday)
client.add_repeat_item(
    food_source_id=12345,
    measure_id=0,        # universal gram-based measure
    quantity=200,
    food_name="Oatmeal",
    diary_group=1,       # 0-based wire index; 1 == Breakfast on a default account
    days_of_week=[1, 2, 3, 4, 5],
)

# Diary groups are user-configured - check what this account actually has
for g in client.diary_groups:
    print(g["wire_index"], g["name"], g["enabled"])

# Log a biometric
client.add_biometric("weight", 218.5, date.today())

License

MIT