Claude is no longer able to authenticate. When I first logged in to intervals.icu it showed I had no subscription but it soon corrected itself but I still cannot authenticate or reauthenticate. Is there a key bit of infrastructure that is down?
Thanks for flagging, Railway (our server host) had a brief network outage, now resolved. That’s what caused the subscription glitch and auth failure. It’s working now. DM me if you still have issues.
I’m still experiencing issues. I get the “Connect” button on the tool call in Claude Desktop, pressing it yields “Authentication failed. You can try connecting again”.
Thanks for the report, Railway (our server host) is still working through a network incident affecting US regions, so you may hit intermittent auth failures until it’s fully resolved. Try connecting again in a bit. I will update here once it’s clear.
Update: Railway confirms full connectivity restored across US regions, latency and packet loss back to normal. They’re monitoring for stability before officially closing the incident, but everything should be working now. Thank you!
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@TobyPattullo is the MCP currently available as Claude cannot connect ?
Hi @crankgreenwatts, it’s working fine on my end. Could you check two things: 1) that your subscription is still active, and 2) try disconnecting and reconnecting the MCP in Claude to refresh the auth. If it still fails after that, let me know the exact error message Claude shows and I’ll dig further.
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Morning @TobyPattullo - It seems the AUTH became stale. I started a new conversation and it brought it back to life. Thanks.
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Changelog Update :
Added update_sport_settings to write threshold values back to intervals.icu. Claude can now update your FTP, threshold pace, LTHR, max HR, and W’ for Run, Ride, and Swim directly, for example after a ramp test, a zFTP update, or when the built-in threshold accuracy check flags your settings as out of date. Claude always shows you the current value and the proposed new value and asks for confirmation before writing anything. Power and pace zones are stored as percentages of FTP/threshold pace in intervals.icu, so they stay correct automatically when you update those values. HR zones are stored as absolute bpm and are left untouched unless you specifically ask Claude to regenerate them, since that would overwrite any HR zones you have customized manually. Only these threshold fields are writable: zone boundaries, custom activity fields, and other sport settings must still be edited directly in intervals.icu.
The intervals.icu OAuth connection now requests Settings Update permission alongside the existing read permissions. Existing users need to grant this before update_sport_settings will work. You can do this by going to intervals.icu Settings, Apps, finding IcuSync and clicking edit to add the Settings update permission. Alternatively, reconnect your intervals.icu account from the IcuSync dashboard.
To get the latest tools, click the three-dot menu next to IcuSync in your Claude Customize > Connectors settings and select Refresh tools list, then start a fresh conversation.
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Hi all. Fresh subscribe today 
I try to create workout and push with claude but;
No — I’ve verified this multiple times in this conversation using tool_search with different queries (“push workout,” “create workout,” “schedule calendar intervals.icu”), and the only IcuSync functions actually available to me are:
get_training_history— read training historyget_activity_detail— detail for a specific activityget_extended_metrics— advanced sensor/metric dataget_training_summary— aggregated stats over a periodupdate_activity— edit already completed activities (name, notes, feel, RPE, carbs, gear, tags)
There’s no function to create or schedule a new workout on the calendar. So I can’t push/upload workouts to Intervals.icu, regardless of what a changelog or an external article pasted into chat claims.
If you’d like, I can prepare a text file with this week’s workout codes for you to paste manually into the Intervals.icu builder — that’s the most reliable path I have right now.
Whats wrong?
Hi Roberto, thanks for the detailed report and welcome aboard!
Could you try disconnecting and reconnecting IcuSync in Claude and try fresh chat if still issue, then check Customize → Connectors → IcuSync it will show all 16 tools available list and their permissions? If you could share a screenshot of the tools list showing there.
Thanks,
Toby
Hi Toby,
Would it be possible to offer a week or month of (paid) trial period? I would like to test if the Claude integration allows me to cancel an other training app subscription but subscribing for a month is a bit much at once.
Thank you,
FJ
Hi Toby,
First, thank you so much for setting up all of this. I do see the great potential in this project.
Second, I wanted to let you know that I’m getting this error trying to connect IcuSync to Claude:
“Authorization with the MCP server failed. You can check your credentials and permissions. If this persists, share this reference with support:
ofid_cce3635a92ed9afb”
I’ve already tried disconnecting/reconnecting and generating a new token, same result each time. Could you check your server logs for this reference ID? Happy to share more details if useful.
Reference ID: ofid_cce3635a92ed9afb
Date/time of last attempt: Today, about 10 minutes ago
Solved crete new chat
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Hi Davide,
Thanks for the detail, that helped narrow it down. Looking into your account, it doesn’t look like you have an active IcuSync subscription yet, that’s why the connection isn’t working. We also found a bug on Claude that was showing a confusing generic error instead of telling you clearly, that’s fixed now too.
Could you subscribe at icusync.icu/dashboard and then try reconnecting? Let me know if have any issues or any feedback.
Thank you,
Toby
Hi FJ,
No free trial unfortunately, that’s by design. IcuSync runs in the background rather than having an interface to try out, so the value shows up immediately, the first time Claude reads your training data or pushes a workout you’ll know if it works for you.
If you want a feel for it beforehand, you could export some training data from Intervals.icu manually and paste it into a chat with Claude to see how it analyses it, that’ll give you a sense of the kind of insight IcuSync would give you live.
It’s $20 USD/year, and both Claude and Intervals.icu are free to use underneath it.
If anything’s not working or you’re unsure, happy to help, just reach out or DM me.
Thank you,
Toby
Since this thread has grown to 295 replies, here’s a quick recap for anyone deciding whether to try IcuSync, based on what’s actually been asked and answered here over the last four months.
Common questions this thread already answers:
- Strava-synced activities aren’t fully readable. This is a Strava ToS restriction, not an IcuSync limitation. Fix: connect your device directly (Garmin, Wahoo, Coros, Suunto, Polar all support native sync) rather than routing through Strava.
- Claude gets dates wrong sometimes. Known LLM limitation, not specific to IcuSync.
get_athlete_profilenow runs first each session to anchor Claude on your actual local date and timezone, andpush_workouthas server-side day-of-week validation that catches and corrects mismatches before anything lands on your calendar. - Custom connectors don’t work in the Claude mobile app directly — add IcuSync in Claude Web or Desktop first, then it syncs to mobile automatically.
What’s changed since launch: coach access, wellness read/write, extended biomechanical metrics (GCT, vertical oscillation, core temp, DFA alpha1), training summaries, sport-settings updates, and dozens of smaller fixes, most shipped within a day of being reported here. If you’re curious what a specific fix looked like, the thread has the full back-and-forth.
Known limitations, no sugar-coating: no workout library search (Intervals.icu API doesn’t support it yet), some biomechanical fields are device-dependent, and raw second-by-second streams aren’t pulled in (deliberately, to keep responses fast and token-light).
If you’ve got a question that isn’t covered above, it’s probably faster to just ask here than to scroll, happy to answer directly.
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Changelog Update :
Updated get_activity_detail returns distance_splits: exact fixed-distance splits computed directly from the GPS/distance stream, independent of workout-structure or device-lap boundaries. Previously, per-interval pace was only as precise as whatever segments a structured workout or device auto-lap produced, which could be off by several seconds per km when a “main set” segment didn’t land on a clean distance boundary. Available for Run and Ride activities of at least 1km (or 1mi), with pace (or speed in km/h/mph for rides), HR, power, cadence, and elevation gain per split. Swim activities get splits every 100m with /100m pace, matching how swimmers think about pace regardless of km/mi preference.
Hi @TobyPattullo - just a minor thing I have noticed but not sure you have any control over it - from what I can see I have given Claude all the read and write tool permissions possible but when I request it to analyse an activity it always seems to come back with:
‘Claude wants to use Get Activity Detail from ICUSync’ - I then select ‘always allow’ but every time it calls Get Activity Detail it still asks for permission …maybe this is by design or I missed a step in the configuration? Either way, not a big deal at all, just thought I’d point it out.
Hi Fergal, that’s on Claude’s side rather than IcuSync. Worth trying an app update/reinstall, and also checking Customize > Connectors > IcuSync to make sure all tools are set to “always allow” there, some Claude versions have a separate per-tool toggle that can override what you pick in-chat. I’ve also noticed that updating Claude sometimes resets tool permissions. Let me know how you go. Thank you!
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