How to Set Up the Relay MCP Server

Introduction

Relay's MCP connection brings your athletes, programs, and exercise library into Claude and other AI apps. Once it is set up, you can ask an assistant to pull up an athlete's week, build a session, or progress a block, and the change lands in Relay.

No API key, no copying and pasting between tabs. This guide covers connecting the apps people ask about most.

Before you start

You need a Relay account with coach or owner access. Athlete accounts cannot connect.

Log into Relay in your browser first. If you start the connection while logged out, the sign-in step loses your place and you have to start over.

The address you will paste is always the same:

https://www.relayathletic.com/api/mcp

Connect to Claude

Go to claude.ai, or open the desktop app.
Select Customize in the sidebar, and choose Connectors. You can also reach it through Settings.
Click Add, then Add custom connector.

The Connectors screen in Claude with the Add menu open, showing the Add custom connector option

Enter Relay as the name and https://www.relayathletic.com/api/mcp as the URL, then click Add.

The Add custom connector dialog with Relay as the name and the Relay MCP address as the URL

Relay now appears in your Connectors list. Select Connect and sign in to finish.

Relay listed in the Connectors table with a Connect button

Connect to ChatGPT

Relay is not in ChatGPT's directory, so you add it yourself in developer mode. This needs a paid ChatGPT plan.

Open Settings, then Security and login, and turn on Developer mode.

ChatGPT's Security and login settings with the Developer mode toggle switched on

Go to Plugins, then Browse plugins, and click the + in the top right.

The ChatGPT Plugins directory with the plus button in the top right corner

In the New Plugin dialog, enter Relay as the Name, leave Connection on Server URL, and paste https://www.relayathletic.com/api/mcp. Set Authentication to OAuth, tick I understand and want to continue, then click Create.

The New Plugin dialog with Relay as the name, the Relay MCP server URL, and authentication set to OAuth

Click Sign in with Relay and approve access.

ChatGPT's Add Relay to ChatGPT dialog with a Sign in with Relay button

ChatGPT warns that custom MCP servers carry risk and that OpenAI has not reviewed them. That warning appears for every custom server, Relay included, which is why the acknowledgement checkbox in step 3 is required.

Coding agents

Claude Code

claude mcp add --transport http relay https://www.relayathletic.com/api/mcp

Then run /mcp and choose to authenticate.

Codex

codex mcp add relay --url https://www.relayathletic.com/api/mcp
codex mcp login relay

Or add it to ~/.codex/config.toml yourself:

[mcp_servers.relay]
url = "https://www.relayathletic.com/api/mcp"
auth = "oauth"

Either way a browser window opens for you to approve access.

Other apps

Any app that supports custom MCP connectors will work with the same address. Relay registers itself automatically, so there is never a client ID or secret to fill in.

Test the connection

First check the connection is live:

Which Relay tools do you have access to?

Then a plain read, so you can see what it reaches without changing anything:

List my athletes.

Once that works, hand over the jobs that would otherwise take an afternoon:

Pull Marco's last eight weeks and build me a progress report I can send him, in my club's colours.

Or attach a research paper to the chat and ask:

Use this study to build a four week program template, with exercises from my library.

Open the result in Relay before an athlete trains it.

We are curious what coaches end up building with this. Send us what you come up with at team@relayathletic.com, and we will write up the use cases worth sharing.