What a custom connector is
On Day 7 you picked a tool from Claude's connector list and signed in. That list is the set of tools Anthropic has already added for you. A custom connector is the same kind of plug, except you add it by hand, using an address the tool gives you.
The address is the tool's MCP server. If a company says its product "works with Claude" or "has an MCP", it has one, and it will usually be on a page called something like MCP, Integrations or AI agents.
Higgsfield puts the latest image and video generation models in one place, for social media, marketing or anything else. It makes a good example because it is a popular custom connection. Swap in any tool that publishes a connector address and the steps are identical.
Before you start
- An account with the tool you are connecting. You sign in to it during setup.
- Any Claude plan. Custom connectors work on Free, Pro, Max, Team and Enterprise. Free accounts are limited to one custom connector.
- On a Team or Enterprise plan, only an Owner can add a custom connector (in Organization settings → Connectors). Once they have, everyone else just connects their own account to it.
The steps
This is the reel, written down, with Higgsfield as the example.
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Copy the connector link from the tool
For Higgsfield, go to higgsfield.ai, open MCP and CLI, choose Claude and copy the link. For any other tool, look for a page called MCP, Integrations or AI agents, or search its help centre for "Claude". Always take the link from the company's own website.
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Open the custom connector form in Claude
Open the Claude desktop app and start a new chat. Click the + button, go to Connectors, then Add connector, then Add custom connector.
You can also get there from Customize → Connectors, click +, then Add custom connector. Same form either way, and it works on claude.ai in the browser too.
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Name it and paste the link
Name it after the tool (Higgsfield AI), paste the link into the URL box and click Continue. Leave the settings as they are. The advanced OAuth fields are only for tools whose own instructions tell you to fill them in.
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Sign in to the tool
Follow the link through to the tool, log in and approve the access. That is the connection made. No API key and no code, just your account talking to Claude.
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Check it is there, and prove it works
Open Manage connectors and you should see it in the list. Connectors are switched on per chat, so in a chat hit +, go to Connectors and make sure it is toggled on. Then ask something only that tool could answer. For Higgsfield, "what is my credit balance?" does it without spending anything. A real answer means you are live.
Decide the permissions
Once the connection is made you will see every action the connector gives Claude, each with its own setting. What you allow is your call, for every custom connector you make. This is the same panel from Day 7.
| Setting | What happens | A sensible default |
|---|---|---|
| Always allow | Claude uses the action without asking. | Anything that only looks something up. |
| Needs approval | Claude asks, and waits for your yes. | Anything that creates, changes, sends or spends. With Higgsfield, that is generating an image or video. |
| Blocked | Claude cannot use that action. | Anything you never want it doing on your account. |
A custom connector gives Claude a live line into someone else's server. Anthropic's own guidance is to connect only to trusted servers, read the permissions carefully, and be aware that a malicious server can hide instructions in what it sends back. Use the address from the company's own website, never one from a comment or a random guide.
When it does not work
- Claude answers without actually using the tool. Check the connector is toggled on in this chat. Then start a new chat and mention the tool by name in the request.
- It says it cannot connect, or the sign-in has expired. Disconnect the connector, reconnect it, and start a fresh chat. That fixes most problems.
- You cannot add a second custom connector. Free plans allow one. Remove the old one or upgrade.
- The option is missing on a work account. Your organisation's Owner has to add custom connectors. Send them the link.
If a tool has no connector address at all, it can still feed Claude through an API key. Day 9 shows how, and how to keep the key safe.
Connectors you add in the Claude app show up in Claude Code automatically when you are logged in with the same account, so there is nothing extra to set up.
Where this goes
Day 7 plugged in the tools Claude already knows. Today covered the ones it does not. Day 9 puts them to work: every morning, Claude pulls the numbers from all of them and has a summary ready before I sit down.
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