What you need
- The Onyx Coach server address:
https://api.onyxcoach.com/mcp - A Claude account. Custom connectors work on the Free, Pro, Max, Team and Enterprise plans. The Free plan allows one custom connector.
- An Onyx Coach trainer account. If you do not have one yet, you can create it during step 4. The 14-day trial needs no card.
Connect on a Free, Pro or Max plan
Do this in Claude on the web or in the Claude desktop app.
- Open Customize, then Connectors. This link goes straight there: claude.ai/customize/connectors.
- Choose Add custom connector. In some accounts it sits behind an Add button.
- Name it Onyx Coach and paste
https://api.onyxcoach.com/mcpas the server URL. If Claude shows authentication settings, keep what it detected and continue. Then click Add. - Click Connect. Claude opens an Onyx Coach page: sign in, or create your account if you are new. A new account is first asked who you will coach, so Claude has someone to build for.
- Read the list of what Claude will be able to do and click Allow access. You go back to Claude with Onyx Coach connected.
The Onyx Coach page stays valid for 15 minutes. If it expires, click Connect in Claude again.
On a Team or Enterprise plan
An Owner adds the connector once for the whole organization, and each coach then connects their own Onyx Coach account.
- Owner: open Organization settings, then Connectors. Select Add, then Custom, and choose Web if Claude asks for the type. Paste
https://api.onyxcoach.com/mcpand click Add. - Each coach: open Customize, then Connectors, find Onyx Coach with the Custom label and click Connect. Sign in to Onyx Coach and click Allow access.
Every coach approves access to their own account. Nobody sees another coach's clients through the connector.
Use it in a chat
Start a chat, click the + button, open Connectors and check that Onyx Coach is switched on. Then ask in your own words:
- "Build Anna a 4-week strength plan, three days a week."
- "Who has not trained this week?"
- "Here is a client's program as a PDF. Add it to Onyx Coach exactly as written."
- "Schedule a leg workout for Peter on Monday."
- "Look at Jana's last four sessions and progress her squat for next week."
Claude asks for your approval before it uses a tool. Whatever it creates comes back with a link that opens it in Onyx Coach, and your client finds it in the Onyx Coach app like anything you built by hand.
Once added, the connector is also available in the Claude apps for iPhone and Android. Adding it is easiest on the web or in the desktop app.
What Claude can and cannot do
Claude gets exactly the permissions shown on the approval page, for your account only.
| Area | Claude can read | Claude can change |
|---|---|---|
| Clients | Your client list, profiles and onboarding answers | Add a client to your roster |
| Workouts and calendar | Saved workouts, logged sessions, scheduled workouts and rest days | Create, edit and delete saved workouts and calendar entries |
| Programs | Your program library and each client's programs | Create, edit, delete and start programs |
| Exercises | Your library and the official library | Create, edit and delete your own exercises |
| Private notes | Your notes on clients | Create, edit and delete notes |
| Check-ins | Measurements and notes clients submitted | Nothing, check-ins are read only |
Claude cannot message your clients, send invites, delete a client or a logged workout, or touch your billing and account settings.
Stay in control
- Set tool permissions. In Claude, open Customize, then Connectors, and select Onyx Coach. Each tool can be set to Always allow, Needs approval or Blocked. Blocking the delete tools means Claude can never delete anything.
- Switch it off for one chat. The + button, then Connectors, turns Onyx Coach off for that conversation.
- Disconnect. Open Customize, then Connectors, and click Remove on Onyx Coach, or use its three-dot menu. Claude stops using your account, and everything it built stays in Onyx Coach.
If you want access ended on our side as well, write to support and we will revoke it.
Using ChatGPT, or nothing at all
Onyx Coach is also an app in ChatGPT. Open Onyx Coach in ChatGPT, connect it, and approve access on the same Onyx Coach page.
You do not have to connect anything. Onyx AI is built into the trainer web app and the mobile app, and it builds workouts and programs from a prompt in the same way.
