How to Connect ChatGPT to Your Booked55 CRM with MCP

Booked55's MCP server at mcp.booked55.com gives ChatGPT direct access to your CRM's tools, from creating contacts to bulk-updating pipeline stages. Once connected, you manage your entire CRM from a conversation.

What you'll need

• A ChatGPT Plus, Pro, Business, Enterprise or Education account, used on the web at chatgpt.com
• A Booked55 account (start with a 14-day free trial)
• An OAuth client ID and client secret from Booked55, made for your ChatGPT app. You ask for them in Step 3 by emailing your Callback URL to [email protected].
• About 10 minutes, plus the wait for our reply

Step 1: Turn on Developer mode in ChatGPT

1. Open chatgpt.com and sign in.
2. Click your profile in the bottom-left corner and select Settings.
3. Select Security and login.
4. Under Developer mode, turn on the Developer mode switch. ChatGPT marks it Elevated risk because it lets you add apps OpenAI hasn't reviewed.

Step 2: Create the Booked55 MCP app

1. Open Plugins from the same Settings menu, or go to chatgpt.com/plugins.
2. Click Add in the top-right corner and choose Create MCP App. The New Plugin window opens.
3. Fill in the left side:
   • Icon and Description are optional.
   • Name: Booked55
   • Connection: keep Server URL selected and enter https://mcp.booked55.com exactly, with no /mcp and no trailing slash.
   • Authentication: OAuth

Step 3: Email us your Callback URL

ChatGPT can't register itself with Booked55, so we make an OAuth client for your ChatGPT app by hand. It only works with the Callback URL ChatGPT gave your app, so every ChatGPT user gets their own client ID and secret.

1. Click Advanced OAuth settings. The OAuth advanced settings open on the right.
2. Under Client registration, keep the Registration method on User-Defined OAuth Client. The notes that DCR and CIMD are unavailable are expected.
3. Copy the Callback URL with the copy button next to it. It looks like https://chatgpt.com/connector/oauth/ followed by a code that is unique to your app.
4. Click Open in your email app below, paste the Callback URL where the email says, and send it. Or copy the email into a message to [email protected]. We reply with an OAuth client ID and an OAuth client secret made for that URL.

Hi,

Please set me up with an OAuth client ID and client secret so I can connect ChatGPT to Booked55.

My ChatGPT Callback URL is:
[paste your Callback URL here]

I sign in to Booked55 with the email address I'm sending this from.

Thanks

Step 4: Enter the client ID and secret, then create the app

1. Paste the client ID into OAuth client ID and the client secret into OAuth client secret.
2. If Token endpoint auth method still says none, change it to client_secret_post. With none, ChatGPT doesn't send the secret and Booked55 refuses the connection.
3. Leave the Scopes as they are.
4. Tick I understand and want to continue and click Create.

Step 5: Authorise with Booked55

1. ChatGPT will redirect you to the Booked55 login page.
2. Sign in with your Booked55 email and password. If you don't have an account, create one for free.
3. Review the requested permissions (read/write access to contacts, companies, tasks, events, and pipelines).
4. Click Authorise.
5. You'll be redirected back to ChatGPT, which lists the tools it found on the Booked55 server. The app is now connected and shows under Drafts in your app settings.

Step 6: Select the app in a conversation

1. Open a new ChatGPT conversation.
2. Click the + button in the message box and choose Developer mode.
3. Select Booked55 for that conversation.

You choose the app per conversation. If ChatGPT answers from its own knowledge instead of your CRM, name the app in your prompt, for example: Use the Booked55 app to find contacts named Sarah.

Step 7: Start using it

That's it. You're connected. Here are some things you can try right away:

ChatGPT can invoke every Booked55 MCP tool, including bulk operations like bulk_add_event_to_contacts. See the full tool list in our MCP overview.

Troubleshooting

The app doesn't appear in my list

Make sure Developer mode is on (Step 1) and that you are using ChatGPT on the web. On Business, Enterprise or Education workspaces, your workspace admin may have to allow it first. In a chat, the app sits behind + → Developer mode.

Create says "Please fill out this field"

The OAuth client ID is empty. ChatGPT needs a client ID before it can create the app, and Booked55 issues one per app: email your Callback URL to [email protected] (Step 3) and enter the client ID and secret you get back.

"The redirect URI does not match one registered for this client"

Your client was made for a different Callback URL than the one this app uses now, for example because you deleted the app and created it again. Email the Callback URL shown in Advanced OAuth settings to [email protected] and we will set up your client for it.

Authorisation fails right after you click Authorise

ChatGPT didn't send the client secret. Check that OAuth client secret is filled in and that Token endpoint auth method is client_secret_post, not none.

You can't sign in to Booked55

Double-check you are signing in with the same email used for your Booked55 account. If you're new, create an account first at dashboard.booked55.com.

Tools aren't responding

Verify the MCP endpoint is set to exactly https://mcp.booked55.com with no trailing slash. If a tool is missing or looks out of date, open Booked55 at chatgpt.com/plugins and select Refresh.

What's next

MCP is still evolving, and so is our integration. We're working on expanding the tool set to include campaign management, template selection, and scoreboard queries. If you have feature requests, reach out. We ship fast.

For the complete technical reference, check out the MCP Server documentation.