FatSecretMcp 0.1.25

fatsecret-mcp

A .NET-based Model Context Protocol (MCP) server for the FatSecret Platform API, installable as a .NET tool from nuget.org. Docker hosting is planned but deliberately deferred - see Security below.

This is an independent, community-built project - not an official FatSecret product. It is not affiliated with, endorsed by, or supported by FatSecret. It works against the public FatSecret Platform API using your own developer credentials, registered separately at platform.fatsecret.com. "FatSecret" is a trademark of its respective owner, used here only to describe API compatibility.

Purpose

FatSecret has years of your food diary, weight, and exercise history sitting behind its own app and website. This project connects that data to an LLM directly, so you can ask questions and log entries in plain language instead of tapping through FatSecret's UI - and, eventually, sync data between FatSecret and other fitness trackers/calorie apps rather than re-entering the same numbers twice.

A couple of examples of what that looks like once the tools are connected (illustrative - your own numbers will differ):

You: How many days this month did I stay below my recommended calorie count?

Claude: Looking at your food diary for August: you logged food on 18 of the 19 days so far. You stayed under your ~2,300 kcal target on 13 of those days, averaging about 2,180 kcal on target days. The 5 over-target days cluster on weekends, averaging around 2,650 kcal.

You: How many weeks did it take me to lose 5 kilos?

Claude: Your weight log shows 84.2 kg on March 3rd and 79.1 kg on June 9th - a 5.1 kg loss over about 13.5 weeks, averaging roughly 0.4 kg/week. The rate was fairly steady, with a plateau in late April where weight held for about two weeks.

Requirements

• .NET 8 or .NET 10 runtime - to install and run the tool (see Install below)
• An MCP-capable LLM client - Claude Code, Claude Desktop, ChatGPT, or LM Studio (see Configure Claude Code, Claude Desktop, or LM Studio below)
• A FatSecret account and API app - your existing FatSecret account, plus a free developer app registered at https://platform.fatsecret.com/ for API credentials

Status

This is a working prototype, already used day to day for real tracking.

See open issues for the current roadmap.

Security

The HTTP transport has no authentication or authorization layer yet - anyone who can reach the endpoint can call any tool, including the ones that read/write your real FatSecret data. This is fine for local use (stdio, or --http left on localhost), but it means this must not be exposed publicly - no public Docker hosting, no binding to 0.0.0.0 on an open network

• until that gap is closed. See docs/multi-tenant-cloud-service.md for the auth work that's needed first and the reasoning behind deferring containerized/cloud hosting.

Available tools

Install

Requires the .NET 8 or .NET 10 SDK - the package multi-targets both, so dotnet tool install picks whichever one matches your installed SDK automatically.

dotnet tool install --global FatSecretMcp

This installs a fatsecret-mcp command. Confirm it's on your PATH with fatsecret-mcp --version (the .NET tools directory, ~/.dotnet/tools, needs to be there - the installer usually adds it automatically).

You'll also need a FatSecret Platform API app - register one at https://platform.fatsecret.com/ if you don't have one.

Configure credentials

Credentials are passed as environment variables - FatSecret:OAuth1:ConsumerKey etc. become FatSecret__OAuth1__ConsumerKey (double underscore in place of :), which is how .NET's config system maps env vars automatically. No code or config file needed.

The access token/secret come from a one-time authorization step, next.

One-time OAuth 1.0a authorization

This grants the server access to your own FatSecret account. It's interactive - you approve access in a browser - but doesn't need a callback server, since FatSecret shows a PIN you copy back in. Do this once, from a terminal, with the consumer key/secret set:

export FatSecret__OAuth1__ConsumerKey="<your consumer key>"
export FatSecret__OAuth1__ConsumerSecret="<your consumer secret>"
fatsecret-mcp auth request

This prints a token, token_secret, and an authorize_url. Open the URL, log in, approve the app, and copy the PIN it shows you. Then:

fatsecret-mcp auth exchange <token> <token_secret> <pin>

This prints an access_token and access_token_secret - it doesn't expire on its own. Add both, plus the consumer key/secret, as environment variables wherever you run fatsecret-mcp from - your shell profile for standalone use, or your MCP client's config for the env block shown below.

Run it

The server supports two transports, chosen at startup - stdio by default, or HTTP via a flag:

fatsecret-mcp                                       # stdio - for MCP clients that spawn the process directly
fatsecret-mcp --http --urls http://localhost:5102    # HTTP - a long-running server on a port

In HTTP mode the MCP endpoint is at <url>/mcp (Streamable HTTP), e.g. http://localhost:5102/mcp.

Configure Claude Code, Claude Desktop, or LM Studio

Do the credentials + one-time OAuth1 steps above first - that part is always interactive and can't happen from inside a client's spawned process.

Can these clients start fatsecret-mcp automatically? Claude Code, Claude Desktop, and LM Studio: yes - all spawn a local stdio process directly from their own config, no server to keep running yourself.

Find the installed binary's absolute path

GUI-launched apps often don't inherit the PATH your terminal has, so the bare fatsecret-mcp command name may not resolve even though it works in a shell. Use the absolute path instead:

• macOS/Linux: ~/.dotnet/tools/fatsecret-mcp
• Windows: %USERPROFILE%\.dotnet\tools\fatsecret-mcp.exe

Claude Code

claude mcp add fatsecret-mcp -- ~/.dotnet/tools/fatsecret-mcp

Restart or reconnect your Claude Code session - new MCP registrations aren't picked up mid-session.

Claude Desktop

Edit claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json; Windows: %APPDATA%\Claude\claude_desktop_config.json):

{
  "mcpServers": {
    "fatsecret-mcp": {
      "command": "/Users/you/.dotnet/tools/fatsecret-mcp",
      "args": [],
      "env": {
        "FatSecret__OAuth1__ConsumerKey": "<your consumer key>",
        "FatSecret__OAuth1__ConsumerSecret": "<your consumer secret>",
        "FatSecret__OAuth1__AccessToken": "<your access token>",
        "FatSecret__OAuth1__AccessTokenSecret": "<your access token secret>",
        "FatSecret__OAuth2__ClientId": "<your client id>",
        "FatSecret__OAuth2__ClientSecret": "<your client secret>"
      }
    }
  }
}

Restart Claude Desktop to pick it up.

LM Studio

LM Studio's MCP config (mcp.json) follows the same command/args/env shape as Claude Desktop above. Its documented path is ~/.lmstudio/mcp.json (macOS/Linux) / %USERPROFILE%\.lmstudio\mcp.json (Windows), but there are user reports of the real path differing by version/OS - rather than guessing, use the in-app editor: Program tab → Install → Edit mcp.json, which opens whichever file is actually authoritative for your install, and paste in the same JSON shown for Claude Desktop above (just the inner object works too, since LM Studio also uses an mcpServers map).

Building from source / contributing

Not needed just to use the tool - see docs/DEVELOPER.md in the repo for running from a clone, architecture notes, and how NuGet publishing works.

License

MIT — see LICENSE.