Connect ChatGPT to Booked55

Follow these steps to connect your ChatGPT account to Booked55 via the MCP server. Once connected you can manage contacts, companies, pipelines, tasks, and events using natural language.

Step 1 — Turn on Developer mode in ChatGPT

ChatGPT only connects to an MCP server you add yourself when Developer mode is on.

Open chatgpt.com and sign in.
Click your profile in the bottom-left corner and open Settings.
Select Security and login.
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

Open Plugins from the same Settings menu, or go to chatgpt.com/plugins.
Click Add in the top-right corner and choose Create MCP App. The New Plugin window opens.
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 nothing after it, 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. A client ID made for Claude will not work here.

Why you email us for a client ID and secret

Your CRM holds your clients' names, phone numbers and deal history, so Booked55 decides which apps may ask for it, not the app itself. This one email is what keeps that access yours:

No app can sign itself up. Many MCP servers let any app register automatically. That would let anyone make an app with a convincing name, point it at their own server, and send you a link to approve. On Booked55, every app is set up by us, by hand.
Your client only works with your app. It is tied to one exact address that the sign-in result goes back to. Booked55 never sends it anywhere else.
The secret proves it is really your app. ChatGPT has to present it every time it collects access, and a one-time check on each sign-in stops an intercepted code from being used.
One client can be switched off on its own. If something looks wrong, we turn off that client and it stops working within the hour, without touching anyone else's connection.
Your password never reaches ChatGPT. You sign in on Booked55's own page, and ChatGPT gets an access key limited to the permissions you approve.

You only do this once for each app. The email below is ready to send, so there is nothing to write.

Click Advanced OAuth settings. The OAuth advanced settings open on the right.
Under Client registration, keep the Registration method on User-Defined OAuth Client. The notes that DCR and CIMD are unavailable are expected.
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.
Paste the Callback URL into the box below, then click Open in your email app, or copy the email and send it to [email protected] yourself. We reply with an OAuth client ID and an OAuth client secret made for that URL.

Paste your Callback URL

To: [email protected]

Subject: Booked55 OAuth client for ChatGPT

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

Open in your email app

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

Paste the client ID into OAuth client ID and the client secret into OAuth client secret.
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.
Leave the Scopes as they are.
Tick I understand and want to continue and click Create.

Step 5 — Authorize with Booked55

ChatGPT opens the Booked55 sign-in page.
Sign in with your Booked55 account (or create an account if you don't have one).
Review the requested permissions and click Authorize.
You are sent 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 chat

Open a new ChatGPT conversation.
Click the + button in the message box and choose Developer mode.
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

Try these example prompts to get started:

Add a contact

Add a new contact: John Smith, [email protected], VP of Sales at Acme Corp.

Search contacts

Find all contacts whose name contains "Sarah".

Create a company

Create a company called "TechStart Inc." based in Toronto.

Search companies

Search for companies with "consulting" in the name.

Create a task

Create a follow-up task for John Smith: "Send proposal by Friday", high priority.

List pipeline deals

Show me all deals in my sales pipeline.

Move a deal

Update the "Acme Corp deal" pipeline item to the "Negotiation" stage.

Log an event

Create an event called "SaaS Connect Toronto" on March 15, 2026.

Pictures in an email template

When ChatGPT writes an email template for you, it also puts the pictures in it. A picture in an email has to sit at a public web address that never expires, so each one is hosted on Booked55 first and the template points there. Attach the pictures to the chat and ChatGPT passes them to Booked55 itself. It can also take a picture that is already on the web, such as the logo on your website, from its address.

If ChatGPT cannot pass a file, it gives you a link instead. Open it, drop the pictures in, and tell ChatGPT you are done. The link works for 30 minutes and takes up to 20 pictures.

Booked55 accepts PNG, JPEG, GIF and WebP pictures up to 5 MB each. It stores its own copy, sized for email, with the camera and location details removed.

Write a welcome email template for new clients. Put the logo I attached at the top and the team photo under the first paragraph.

Your design system

Your organization has one shared design system: a small folder of text files (colours, fonts, spacing, reusable HTML and CSS) and a running file of notes about what was decided. ChatGPT reads it before it designs an email template or anything else branded, such as a flyer or a social post image, so everything it makes for you looks like yours.

It starts empty. Once you are happy with a look, ask ChatGPT to save it, and to note what you decided. The next conversation, yours or a teammate's, starts from there.

Save this colour palette and button style as our design system, and note that buttons are always teal.

Troubleshooting

Create does nothing and 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.

Authorization fails right after you click Authorize

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.

I can't create the app, or it doesn't appear in a chat

Check that Developer mode is on under Settings → Security and login, and that you are using ChatGPT on the web. On a Business, Enterprise or Education workspace, your workspace admin may have to allow Developer mode first. An app you created shows under Drafts in your app settings, and in a chat it sits behind + → Developer mode.

A tool is missing or looks out of date

Open Booked55 at chatgpt.com/plugins and select Refresh to pull the current tool list from the server. The same page lets you switch individual tools on or off.

You can't sign in to Booked55

Verify you are signing in with the same email used for your Booked55 account. If you don't have an account yet, create one for free.

Tools are not responding

Check that the MCP endpoint is set to exactly https://mcp.booked55.com with no trailing slash. If issues persist, disconnect the app and reconnect it.

Next steps

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