Intervals.icu
in Gemini.
IntervalSync is a hosted MCP server for Intervals.icu. Add it to Gemini once as a custom app, sign in with your Intervals.icu account, and Gemini can read your activities, intervals, per-second streams, wellness and planned workouts when you ask about them.
There is no API key to paste into Gemini and nothing to install. Gemini gets a short-lived, revocable token for your training connection, and never sees your Intervals.icu credential.
Who can add a custom app.
As of 14 October 2026, Google's page on custom apps for Gemini says you need to:
- be 18 or over and in the US;
- sign in to Gemini with a personal Google Account: custom apps are not available on a work or school account;
- have Keep Activity turned on, because custom apps are unavailable without it.
Google also says custom apps are, for now, only in English, and only in the Gemini web app and the Gemini mobile app. You add one on the web; once it is connected, it works in the mobile app too. Google's page names no Gemini subscription as a requirement. Google changes these rules, so read their page for where they stand before you rely on this one.
IntervalSync has plans of its own too. Reading works on every plan, and writing needs the 14-day trial, Pro or a Coach plan: pricing has each one, and the terms set out the rules.
Add IntervalSync to Gemini.
These are the steps as Google describes them on 14 October 2026.
- On a computer, go to gemini.google.com.
- At the bottom, select Settings, then Connected Apps. If Connected Apps is not there, select Personal Intelligence first.
- Under Custom apps, select Add a custom app.
- Enter the server URL:
https://intervalsync.icu/mcp/v2 - Leave Advanced features as it is: IntervalSync registers Gemini itself, so there are no credentials to enter.
- Select Next, and complete the IntervalSync sign-in with your Intervals.icu account.
- In a chat, type @, select IntervalSync, and ask: List my last three activities.
Why nothing goes under Advanced features. Google asks for credentials there only when a server does not support Dynamic Client Registration. IntervalSync does: it registers each assistant that connects.
Nothing changes until you confirm it.
Four IntervalSync tools change your Intervals.icu data: they create, update and delete planned workouts, and update wellness records. Each one shows you the exact change before it is made, and nothing else on the workout is touched. Google says Gemini also asks you to confirm any write action itself.
The common fixes.
There is no Custom apps section in Connected Apps.
Google offers custom apps only to people 18 or over in the US, on a personal Google Account, with Keep Activity turned on. A work or school account does not have it.
Gemini does not use IntervalSync.
Type @ and select IntervalSync in the message that needs your training.
I want to disconnect or remove it.
In Settings, then Connected Apps, under Custom apps: turn IntervalSync off to disconnect it, select More details, then Disconnect, to unlink it from your Google Account, or More details, then Remove app, to remove it.
A tool says a permission is missing.
Intervals.icu lets you choose which permissions to grant. Open IntervalSync, select Settings, go to AI Vendor Connections and choose Refresh Intervals permissions if it is shown, or sign out and sign back in, and approve the one that was left out. Do not paste an API key into Gemini.
A tool says a daily limit was reached.
Every IntervalSync plan has a daily limit on calls to Intervals.icu, and the message says when the count starts again. The terms set out each one.
Still stuck? Support has the rest, and a form that reaches the people who build IntervalSync.
Once it is connected.
Ask about a date range and a decision rather than "how is my training?". The prompt library has questions that work, and questions with no chart shows what an assistant can answer that Intervals.icu has the data for but no chart.
The Intervals.icu MCP server · Support · Connect your training