Intervals.icu
in Claude.
IntervalSync is a hosted MCP server for Intervals.icu. Add it to Claude once as a custom connector, sign in with your Intervals.icu account, and Claude 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 Claude and nothing to install. Claude gets a short-lived, revocable token for your training connection, and never sees your Intervals.icu credential.
Which Claude plan you need.
As of 14 October 2026, Anthropic's page on custom connectors says:
Custom connectors work in Claude on the web, in Claude Desktop and in Cowork, and Anthropic's page says Claude reaches the server from Anthropic's own servers in every Claude app, the mobile apps included. Anthropic 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 Claude.
These are the steps for Free, Pro and Max, as Anthropic describes them on 14 October 2026.
- In Claude, open Customize, then Connectors.
- Select + Add, then Add custom connector.
- Name it IntervalSync.
- Enter the server URL:
https://intervalsync.icu/mcp/v2 - Select Continue, keep the authentication settings Claude detects, and select Continue again.
- Under Authentication, choose Sign in now.
- Under OAuth client, choose Register automatically. Leave Request headers empty.
- Select Add, and complete the IntervalSync sign-in with your Intervals.icu account.
- In a chat, select +, then Connectors, turn IntervalSync on, and ask: List my last three activities.
Why Register automatically. Claude's recommended option, its published identity, works only with a server that says it supports it, and IntervalSync does not: it registers each assistant that connects, which is what Register automatically does. Anthropic says Claude falls back to that by itself when a server does not support the published identity.
If your dialog shows one screen with a name, a URL and Advanced settings, enter the name and the URL, and leave the OAuth client ID and secret under Advanced settings empty.
On Team or Enterprise, an Owner goes to Organization settings → Connectors, selects Add, then Custom, then Web, and makes the same choices. Members then open Customize → Connectors, find IntervalSync with its Custom label, and select Connect.
One command in the terminal.
Claude Code adds the server from the command line. Run this, then type /mcp in Claude Code to sign in:
claude mcp add --transport http intervalsync https://intervalsync.icu/mcp/v2
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. Claude also asks before it uses a tool unless you have chosen to always allow it.
Anthropic says that in Research, Claude can use a connector's tools without asking, and recommends turning off tools that write. You can block any one tool under Customize → Connectors, by selecting IntervalSync and setting that tool's permission to Blocked.
The common fixes.
Claude says IntervalSync is connected, but does not use it.
A connector is turned on per conversation. Select + in the chat, then Connectors, and turn IntervalSync on for that conversation.
Claude will not let me add another custom connector.
On Free, Anthropic allows one custom connector. Remove the one you have under Customize → Connectors, or use a paid Claude plan.
I chose the wrong sign-in settings.
Anthropic says a connector's authentication settings cannot be changed after it is added. Remove IntervalSync under Customize → Connectors and add it again.
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 Claude.
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