- The catch: Anthropic's cloud makes the call, not your laptop
- Remote connector or local extension: which route fits
- Adding a remote MCP server on Pro or Max
- Team and Enterprise: owners add it, members connect
- Installing a local desktop extension
- Switching connectors on, and editing them
- Safety rules before you connect anything
- My verdict on MCP in Claude
- Frequently asked questions
There are two ways to plug an MCP server into Claude: a remote custom connector, where you paste a server URL and Anthropic's cloud connects to it, or a local desktop extension (an .mcpb file) that runs on your own computer inside Claude Desktop. As of October 2026 remote connectors work on Free, Pro, Max, Team and Enterprise plans (Free is limited to one custom connector), while local extensions only work in Claude Desktop.
MCP, the Model Context Protocol, is the open standard Anthropic created so AI apps can connect to tools and data. Early on, MCP servers only ran locally on your laptop; now developers also host remote servers that talk to Claude over the internet, which is why there are two routes.
The catch: Anthropic's cloud makes the call, not your laptop
This is the one that wastes an afternoon. When you add a custom connector, Claude doesn't connect to your remote MCP server from your device. It connects from Anthropic's cloud infrastructure, and that's true in every client: claude.ai, Claude Desktop, Cowork and the mobile apps.
So the server has to be reachable over the public internet from Anthropic's IP ranges. If it sits on a private corporate network, behind a VPN or behind a firewall that blocks outside traffic, it won't connect, even though you can open it perfectly well from your own machine. Anthropic's fix, as of October 2026, is to allowlist its published IP addresses.
If the server can't be opened up like that, the local route is the way round it. Local MCP servers set up in Claude Desktop through claude_desktop_config.json use your local network instead, though Anthropic treats them as a separate mechanism and they don't show up in Cowork or claude.ai.
Remote connector or local extension: which route fits
| Route | How it connects | Needs | Where it works |
|---|---|---|---|
| Remote custom connector | Anthropic's cloud calls your server URL | Public internet reachable from Anthropic IP ranges | Claude, Cowork, Claude Desktop, mobile |
| Local desktop extension (.mcpb) | Runs on your computer | Claude Desktop installed | Claude Desktop only, not claude.ai or Cowork |
Here's the short version of the whole job, before the detail for each plan.
- Decide: remote server (a URL) or local extension (an .mcpb file).
- Remote: Customize > Connectors > + Add > Add custom connector, paste the URL and set authentication.
- Local: Settings > Desktop app > Manage next to Extensions, browse or install the .mcpb file.
- Enable the connector for the conversation via + > Connectors.
- Limit its tools in Search and tools and approve actions one at a time.
If you only want the ready-made integrations Anthropic lists in its directory, you don't need any of this. My guide to Claude's built-in connectors covers those.
Adding a remote MCP server on Pro or Max
On an individual plan you do it yourself from Customize > Connectors. Click + Add, choose Add custom connector, give it a name and paste the remote MCP server URL. Claude then shows the authentication settings it detected, and you choose how it should sign in.
- Authentication. Sign in now, Sign in when needed, or No sign in.
- OAuth client. Claude's published identity (the one Anthropic recommends), Register automatically, or your own OAuth client.
- Request headers. Optional, for servers that want an API key or a bearer token.
Click Add and it's saved. Fixed credentials like those headers are stored encrypted, as of October 2026.
Team and Enterprise: owners add it, members connect
On shared plans most people can't add a custom connector at all. On Team, only Owners and Primary Owners can. On Enterprise, it's Owners, Primary Owners and anyone with a custom role that includes Manage access to Libraries.
They go to Organization settings > Connectors, click Add, hover over Custom and select Web, then fill in the same name, URL, authentication, OAuth client and request header settings. Members then open Customize > Connectors, find the connector (usually labelled Custom) and click Connect.
Each person connects individually, so Claude only reaches the data that person can already see. The exception is a connector built on a shared credential such as an API key: then everyone gets the same access, which is worth thinking hard about before you set one up.
Installing a local desktop extension
Desktop extensions are single-click packages for local MCP servers on Claude Desktop. To install one from the directory, go to Settings > Desktop app, click Manage next to Extensions, then Browse extensions and Install. To install your own .mcpb file, use Advanced settings > Extension Developer > Install Extension.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
On Team and Enterprise, admins can switch public desktop extensions on or off and upload custom ones so staff get a one-click install. Enterprise policy controls set at the machine level override the in-app allowlist and blocklist, so if an extension won't appear on a work laptop, that's the first place I'd look.
When a local extension misbehaves, Anthropic's checklist is short. If it won't install, update Claude Desktop, download the file again and check your disk space. If it installed but the tools are missing, restart Claude Desktop and check the required fields and API keys in the extension's settings.
Switching connectors on, and editing them
Adding a connector doesn't switch it on everywhere. You enable connectors per conversation with the + button at the lower left of the chat, then Connectors, using the toggles. That's handy if you work across Claude Cowork and chat, because you only switch on what each task needs.
There's also no edit button. To change a custom connector's URL or settings, you remove it and add it again with the new details.
Safety rules before you connect anything
A custom connector can link Claude to a service Anthropic hasn't verified, and Claude can then read, change or delete data in it within your permissions. Anthropic's own advice, as of October 2026:
- Only connect to servers you trust.
- Review the permissions it asks for and limit scopes.
- Watch for prompt injection from a malicious server.
- Keep an eye on changes in how its tools behave.
- Switch off tools you don't need in the Search and tools menu, and be careful with Allow always.
My verdict on MCP in Claude
I'd use a remote custom connector if your server is already on the public internet and you want it everywhere, including your phone and Cowork. I'd use a local desktop extension if the data lives on your machine or inside a private network you can't open to Anthropic's IP ranges. Either way, start with tools set to ask before acting, and only loosen that once you've watched it work. If you're packaging connectors and skills together for a team, plugins in Claude are the next thing to read.
Frequently asked questions
Why won't my custom MCP connector connect to Claude?
Claude reaches remote MCP servers from Anthropic's cloud, not your device. A server behind a VPN, firewall or private network won't connect until you allowlist Anthropic's published IP addresses.
Can I use MCP on the free Claude plan?
Yes. As of October 2026 Free users can add custom connectors using remote MCP, limited to one.
Do local MCP servers work on claude.ai?
No. Local servers and desktop extensions run through Claude Desktop only, not claude.ai or Cowork.
How do I edit a custom connector?
You can't edit it in place. Remove the connector and add it again with the new details.
