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— Why MCP

Why the logbook is MCP-first.

Model Context Protocol (MCP) is the open standard that lets AI assistants discover and call external tools. Verxion is built on top of it because the AI you already use should be the interface — not another app.

What is MCP

The Model Context Protocol is an open protocol introduced by Anthropic in 2025 and now adopted by ChatGPT, Claude, Cursor, Claude Code and a growing list of AI clients. It defines how an AI agent discovers, authenticates against, and calls tools on a remote server. The agent reads a structured catalog, calls tools with typed inputs, and reasons over typed responses.

For Verxion, each fitness action — logging a set, querying weekly volume, importing a routine, scanning a barcode — is an MCP tool the agent can call. Because the protocol is open, the same logbook works in every MCP-compatible client.

Why MCP for fitness

Three reasons.

First, the interface is already open. Athletes who use AI assistants daily already plan workouts and debug nutrition there. Forcing them into a separate app for logging creates friction at the exact moment they have the most context.

Second, switching clients is free. Move from ChatGPT to Claude tomorrow — same data, same OAuth tokens, same recipes. The data lock-in that's normal for fitness apps doesn't exist on MCP.

Third, reasoning over data is conversational. "What changed in my pull-day volume over the last mesocycle?" is a one-line question. The agent calls the analytics tools, reads the response, and answers. No charts to interpret.

Verxion's MCP design

Verxion exposes a single execute_code tool in its default profile. Behind that tool, the AI agent has access to the full domain — training routines, sessions, set logs, advanced sets, diet plans, meals, foods, supplements, body measurements, analytics and social. The agent writes a short TypeScript snippet that calls the domain methods it needs and gets typed responses back.

OAuth is granular. Each integration gets a token scoped to the domains it needs. Scopes are revocable from the user's account page. Tokens are short-lived; refresh tokens are rotated.

The MCP server is OAuth-protected via the protected-resource pointer at /.well-known/oauth-protected-resource. Discovery is wired to /.well-known/openid-configuration on the authorization server (the Verxion API).

Compatible clients

  • ChatGPT (Web, Desktop, Mobile) with interactive widgets + voice mode
  • Claude Desktop (macOS, Windows)
  • Claude Code (CLI)
  • Cursor
  • Any MCP-compatible AI agent — Verxion follows the standard protocol

See the setup page for one-click configuration tokens for each client.