The Crystal MCP server for Claude, ChatGPT, and Copilot.

Crystal publishes an official open-source Claude Code plugin. No OAuth client to create and no key to paste: it registers with the MCP server the first time you use it and opens a sign-in in your browser. It also ships two skills, premeeting (DISC-tailored call prep, pulling attendees from your calendar) and transcript-analysis (a personality-grounded call debrief).

/plugin marketplace add crystal-project-inc/crystal-knows-plugin
/plugin install crystal-knows@crystal-knows-marketplace

Or run /plugin, open Discover, and pick Crystal Knows. Rolling it out to a team? Create a Claude connection on the data dashboard and pin its client ID in the plugin’s .mcp.json:

{
  "mcpServers": {
    "crystal": {
      "type": "http",
      "url": "https://api.crystalknows.com/_mcp",
      "oauth": {
        "clientId": "your-client-id",
        "callbackPort": 8080,
        "scopes": ""
      }
    }
  }
}

Every other client: create a connection

Sign in at data.crystalknows.com/mcp and create a connection for the client you are using: Claude, ChatGPT, or Microsoft Copilot. Each connection has its own client ID and secret, plus the authorization, token, and refresh URLs some clients ask for. Save the secret somewhere safe; it is only shown once. Clients that cannot run OAuth (Cursor, custom tooling) skip this step and use an API key instead; see step 7.

Point your client at the server

Every client uses the same server URL. Choose OAuth as the auth method and enter the client ID and secret from the connection you created in step 2. Client-specific walkthroughs follow.

https://api.crystalknows.com/_mcp

No scopes are used. Claude’s callback URL is pre-registered; ChatGPT and Copilot show you one during setup that you register on the connection.

Claude.ai and Claude Desktop

Claude supports custom MCP connectors directly from its settings. To add Crystal:

1. 1.On the data dashboard MCP page, create a Claude connection and copy its client ID and secret. Then in Claude, go to Settings → Connectors → Add custom connector.
2. 2.Set the Name to Crystal and the Remote MCP server URL to https://api.crystalknows.com/_mcp.
3. 3.Expand Advanced settings and paste the OAuth Client ID and OAuth Client Secret from your Claude connection.
4. 4.Click Add, then connect and complete the Crystal OAuth flow when prompted. Claude’s callback URL is already registered on Crystal’s side.

ChatGPT

1. 1.In ChatGPT, open Settings → Connectors and click Create (or Add custom connector) under the Developer mode section.
2. 2.Set the Name to Crystal and the MCP server URL to https://api.crystalknows.com/_mcp.
3. 3.Choose OAuth as the authentication method. Under Advanced OAuth Settings, select User-Defined OAuth Client, then paste the client ID and client secret from the ChatGPT connection you created on the data dashboard.
4. 4.Copy the callback URL that ChatGPT shows you, then register it on your ChatGPT connection on the data dashboard MCP page and save.
5. 5.Save the connector in ChatGPT, then connect and complete the Crystal OAuth flow when prompted.

Microsoft Copilot

1. 1.Create a Microsoft Copilot connection on the data dashboard MCP page.
2. 2.In Copilot Studio’s connector settings, add a new MCP connector with the server URL https://api.crystalknows.com/_mcp, then paste the client ID and secret plus the authorization, token, and refresh URLs and scope shown on your connection.
3. 3.Copy the callback URL Copilot shows and register it on your Copilot connection on the data dashboard.
4. 4.Save, then connect and complete the Crystal sign-in when prompted.

Cursor, agent frameworks, and other clients

For clients that cannot complete an OAuth flow, create an API key at data.crystalknows.com/api-keys and embed it in the server URL:

https://api.crystalknows.com/_mcp/tkn/<your-api-key>

Treat that URL like a credential. Anyone with it can call the MCP server as you, so keep it out of shared configs and rotate the key if it leaks.

Verify it’s working

To confirm the integration is active:

1. 1.Complete the OAuth flow in your MCP client (sign in with Crystal when prompted).
2. 2.Check that your client lists the Crystal MCP tools (search, fetch, selling_to, revise_email, and so on).
3. 3.Try one: ask for your own profile (get_myself), or search for a colleague by email, and confirm you get a response.