Claude MCP: add a custom connector (free plan included)

Updated 30 October 2026. Steps taken from Anthropic's official help centre, read on 30 October 2026. Claude's menus change: if a label has moved, the principle stays the same.

To add an MCP server to Claude, open Customize → Connectors, click “+ Add” then “Add custom connector”, enter a name and the server URL, choose how to sign in, then click Add. In a chat, turn it on with the “+” button at the lower left → Connectors. It works on every plan: the free plan is limited to one custom connector.

This guide uses Pryzm Memory as the example: a persistent memory shared across several AIs over MCP (Model Context Protocol). The steps are the same for any remote MCP server. A section at the end covers Claude Code. Source: Anthropic's help article on custom connectors.

What you need

• A Claude account, on any plan: Free (one custom connector), Pro, Max, Team or Enterprise.
• Claude on the web or the desktop app. Connectors are added from either of these.
• The MCP server URL. For Pryzm: https://pryzm-memory.com/mcp.
• An account with the service you connect. Pryzm is free up to 100 memories. On the free plan, your email must be confirmed before you connect an AI.

The steps in Claude

1. Open connectors. In Claude, open Customize, then Connectors.
2. Add one. Click “+ Add”, then “Add custom connector”.
3. Name it and paste the URL. For example “Pryzm Memory” and https://pryzm-memory.com/mcp, then Continue.
4. Set up sign-in. Choose “Sign in now”. For the OAuth client, choose “Register automatically”: Pryzm supports dynamic client registration.
5. Click Add, then sign in on the service's page. For Pryzm, enter your Pryzm username (the one you picked at sign-up, not your email) and password. Claude receives its own access token.
6. Turn it on in the chat. Click “+” at the lower left of the message box, then Connectors, and switch Pryzm Memory on.

To test it, ask a question that forces Claude to use the connector: “Search my Pryzm memory for what you know about my current projects.” Claude shows the tool call before answering, and may ask for your permission the first time.

“Add custom connector” greyed out or missing

• Free plan: only one custom connector is allowed. If you already have one, remove it before adding another, or move to a paid plan. For a memory like Pryzm, one is enough: the same connector searches, saves and gives project overviews.
• Team and Enterprise: an organisation Owner adds the connector first, under Organization settings → Connectors → Add → Custom → Web. Each member then goes to Customize → Connectors and signs in with their own account.

Get Claude to check the memory on its own

A connector only helps if Claude thinks of using it. To make it check the memory at the start of every conversation and save what matters without being asked, add an instruction: click your initials at the lower left, then Settings → Your Claude → Instructions (in the older layout: Settings → Account → “Instructions for Claude”). Per Anthropic's help centre, these instructions apply to all your conversations.

For Pryzm, the ready-to-paste text is on the connection page, in the “main memory” section.

Claude's built-in memory can overlap with an external one. It is controlled in Settings → Your Claude, with the “Memory from chats” toggle. See what Claude's memory keeps.

Claude Code: a single command

In Claude Code, Anthropic's command-line tool, a remote MCP server is added from the terminal. The --scope user option makes it available in all your projects; without it, it only applies to the current folder (the default “local” scope, per the Claude Code docs).

claude mcp add --transport http --scope user pryzm https://pryzm-memory.com/mcp

• Authenticate. Nothing opens after the command: start Claude Code, type /mcp, pick “pryzm”, then Authenticate. Your browser opens the Pryzm sign-in page.
• Check. claude mcp list shows “pryzm”; until you sign in, its status says it needs authentication.
• Add the instruction. Paste the “main memory” instructions into ~/.claude/CLAUDE.md so they apply to all your projects.

The details, including signing in from an SSH session, are in our Claude Code guide.

Limits worth knowing

• One custom connector on the free plan. No more.
• Menus change. Anthropic updates the interface regularly; exact labels may differ from this guide.
• You are responsible for the server you plug in. A custom connector is not reviewed by Anthropic the way a connector from its directory is: only connect servers whose publisher you know.
• The server sees what Claude sends it. At Pryzm, each account is encrypted with its own key (AES-256-GCM), with servers in Germany; but during a session, the server decrypts your memories in memory so it can search them. It is not end-to-end encryption.

If something doesn't work

• “Incorrect username or password” on the Pryzm page: you typed your email. Use your Pryzm username.
• Error when adding: check the URL, with no space or trailing slash, and that the OAuth client is set to “Register automatically”.
• Sign-in fails: allow pop-ups for claude.ai and check that your Pryzm account's email is confirmed.
• Connected, but Claude doesn't use it: turn the connector on in the chat (“+” → Connectors), then add the instruction.

When it isn't useful

If you only use Claude, its built-in memory and projects are probably enough. An external memory like Pryzm helps when you also work with ChatGPT, Perplexity, Cursor or Gemini CLI, and want them to share the same context.

For ChatGPT, see how to connect ChatGPT to an external memory. Guides for every AI are on the connection page.