MCP server

@almostjacked/fitness-tools-mcp is a Model Context Protocol stdio server. It exposes the same calculators as the library and the HTTP API — identical math — as MCP tools, one tool per calculator. No install required:

npx @almostjacked/fitness-tools-mcp

Works with any MCP-compatible client (Claude Code, Claude Desktop, Cursor, Windsurf, Zed, Cline, Continue, and others).

Add it to a client

Claude Code

claude mcp add fitness-tools -- npx -y @almostjacked/fitness-tools-mcp

Claude Desktop / generic client config

{
  "mcpServers": {
    "fitness-tools": {
      "command": "npx",
      "args": ["-y", "@almostjacked/fitness-tools-mcp"]
    }
  }
}

What the agent sees

Each calculator is a separate MCP tool (tdee, body-fat, one-rep-max, macros, activity-multiplier, powerlifting-attempts, muscle-potential, ffmi, rsmi), with an input schema generated from the same Zod definition that powers the library. Optional fields apply their defaults — e.g. tdee runs all four formulas unless you pass methods.

A call returns both structuredContent (validated against the calculator’s output schema) and a JSON text fallback. So a tdee call with:

{
  "sex": "male", "age": 30,
  "height": { "value": 180, "unit": "cm" },
  "weight": { "value": 80, "unit": "kg" },
  "activity": "moderate"
}

comes back with results (mifflin, harris, …) and a consensus, the same shape the HTTP API and the library return.

Invalid input and domain errors (e.g. an unknown method) come back as tool errors (isError: true) with a readable message — the server never crashes the session.

Library vs. HTTP API vs. MCP

Same calculators, three protocols:

• @almostjacked/fitness-tools — import and call in-process (browser or server).
• @almostjacked/fitness-tools-api — call over HTTP from any language or a no-code tool.
• @almostjacked/fitness-tools-mcp — wire the calculators into an agent or LLM client.