Connect AI assistants

Assistants connect through the CallSlot MCP server. It gets the same tools as the API:

• Bookings: list, view, create, reschedule, ask a guest to reschedule, update details, cancel, or cancel a whole series.
• Availability, and the guest's manage link.
• Booking pages and the event types each one offers.
• Event types, teammates, and hosts: list teammates, add or remove a teammate on a booking, and change a booking's host.
• On The Fly Links: create, list, view, edit, copy the URL again, rotate, or revoke.
• Guest emails saved on an event type: list, save, or reset.

Members, billing, API keys, webhooks, and other space settings stay in the app.

The server URL is https://app.callslot.app/api/mcp. You can also copy it from Settings → Connections.

• Your space must be on the Pro plan. The server refuses sign-ins and keys from other plans.
• Only the space owner can connect an assistant, by signing in or with an API key.
• Claude and ChatGPT connect when you sign in with your CallSlot account. You do not need an API key. Claude Code can sign in or use a key. Cursor and other clients that send headers use an API key.

These steps work in claude.ai, Claude Desktop, and the Claude mobile app.

1. Open Customize → Connectors and choose Add custom connector.
2. Name it CallSlot and paste the MCP server URL: https://app.callslot.app/api/mcp.
3. Leave Advanced settings empty and choose Add.
4. Choose Connect. CallSlot opens. Sign in, pick the space, and allow access. See How signing in works.
5. In a chat, open +, then Connectors, and turn CallSlot on.

Team and Enterprise plans. An Owner adds the connector first, in Organization settings → Connectors → Add → Custom → Web. Then each member opens Customize → Connectors, finds CallSlot, and chooses Connect.

ChatGPT connects custom apps in developer mode, on the web. OpenAI decides which plans get it. On Business, Enterprise, and Edu, an admin may have to turn it on first.

1. In ChatGPT settings, turn on Developer mode.
2. Create a developer mode app for a remote MCP server. Name it CallSlot and paste the MCP server URL: https://app.callslot.app/api/mcp.
3. For authentication, choose OAuth. Leave the client ID and secret empty.
4. Create the app. CallSlot opens. Sign in, pick the space, and allow access. See How signing in works.
5. In a chat, pick CallSlot from the developer mode tools.

ChatGPT often changes where these menus are. If a step does not match, look for developer mode in OpenAI's own help. Do not paste an API key into a ChatGPT chat.

1. Sign in to CallSlot with the account that owns the space. Guest accounts cannot connect an assistant.
2. Pick one space. The assistant can reach only that space. The list shows only the spaces you own that are on Pro.
3. Allow access. The next screen shows the app, the site it sends you back to, the space, and what the app may do, each with a checkbox. Clear a checkbox to keep the app from doing that thing. The app does not see tools you did not allow.
4. You go back to the assistant, and it is connected.

• Apps on your computer. Claude Code sends you back to an address on your own computer. The consent screen warns you about this. Allow it only if you started the sign-in yourself.
• More permissions later. If the app needs a permission you did not allow, it can send you to sign in again and ask for it.

Open Settings → Connections. Under Connected apps, choose Disconnect next to the app. It loses access to the space at once. To use it again, sign in again.

Removing the connector in Claude or ChatGPT might not end its access in CallSlot. Disconnect it in CallSlot too.

Run this command in your terminal:

claude mcp add --transport http callslot https://app.callslot.app/api/mcp

Then, in Claude Code, run /mcp, pick callslot, and choose Authenticate. Your browser opens CallSlot. Sign in, pick the space, and allow access.

To use an API key instead, send it in a header:

claude mcp add --transport http callslot https://app.callslot.app/api/mcp --header "Authorization: Bearer YOUR_API_KEY"

Replace YOUR_API_KEY with your key. Do not save the command with a real key in a file you share or commit.

Cursor, and other MCP clients that accept a URL plus headers, take a config like this:

{
  "mcpServers": {
    "callslot": {
      "url": "https://app.callslot.app/api/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

Replace YOUR_API_KEY with your key. Never put the key in the URL. A client that takes only a URL can still connect if it supports MCP sign-in (OAuth).

• The space owner creates an API key in Settings → API keys. The key is shown once, so copy it then.
• Keep the key secret. Anyone who has it can manage the bookings in your space. Do not paste it into a chat, and do not commit it to code.
• Create one key for each assistant. Then you can revoke one key without breaking the others.
• Every request sends the key in a header: Authorization: Bearer YOUR_API_KEY. Replace YOUR_API_KEY with your key, and keep the word Bearer and the space after it.
• If you only want the assistant to answer questions — look up bookings, open times, and links — create the key with Read only. It cannot book, move, cancel, or change anything, and it cannot get guest manage links.

• Your space is not in the list when you sign in. The list shows only spaces you own that are on Pro. Ask the owner to connect it, or upgrade it in Settings → Billing.
• 401 Unauthorized. For an app you signed in to, the app was disconnected or you can no longer connect the space. Sign in again. For an API key, the key is missing, wrong, revoked, or expired. Copy the key again, or create a new one.
• 400 Bad Request before any tool runs. The Authorization header does not start with Bearer and a space. Set it to Bearer YOUR_API_KEY.
• 403 with SPACE_NOT_PRO. The space is not on the Pro plan. Upgrade it in Settings → Billing.
• 429 with RATE_LIMIT_EXCEEDED. The space made more than 60 requests in a minute. The API and the MCP server share this limit, and so do all the keys in the space. Wait the number of seconds in the Retry-After header. You also get 429 after too many tries with a wrong key.
• DAILY_EMAIL_LIMIT_EXCEEDED. Tools that email a guest (book, reschedule, and ask a guest to reschedule) are capped at 200 per space per day, shared with the API. The count resets at midnight UTC.
• INSUFFICIENT_SCOPE. The key or the sign-in does not allow what that tool needs. The assistant also does not see tools it cannot use. For a key, create a new key with that scope in Settings → API keys. For an app you signed in to, sign in again and allow that permission.

The MCP server only answers when an assistant asks. To get a request each time a booking is made, moved, or cancelled, set up webhooks. See the webhooks guide.