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Integration Guide

Set up the Crystal MCP Server

The Crystal MCP server exposes personality insights to any tool that supports the Model Context Protocol, including Claude, ChatGPT, Cursor, Windsurf, and other MCP-compatible clients. This guide walks you through self-serve OAuth2 setup and adding Crystal as a custom connector in Claude and ChatGPT.

Overview

What this integration does

The Crystal MCP server lets AI assistants look up personality profiles (DISC, MBTI, Enneagram), fetch communication tips, get your own profile and upcoming meetings, and manage profile tags. Once connected via OAuth2, your MCP client can call these tools on your behalf.

Before you begin

Prerequisites

Before you begin, make sure you have:

  • An MCP-compatible client

    For example Claude, ChatGPT, Cursor, Windsurf, or another tool that supports the Model Context Protocol.

  • A Crystal Knows account

    With access to the MCP server.

  • OAuth2 credentials you generate yourself

    Generate your own client ID and client secret from the self-serve page in the Crystal app. Standard MCP client callback URLs are registered for you automatically.

Setup

Connect Crystal to your MCP client

Generate your own credentials, point your client at the server, and verify the tools appear.

  1. 1

    Generate your client ID and client secret

    Sign in to Crystal and open the self-serve MCP page at crystalknows.com/app/team/mcp-server. From there you can generate a client ID and client secret. The standard OAuth callback URLs are registered automatically when credentials are issued, so there’s nothing to configure on Crystal’s side. Save the secret somewhere safe; it’s only shown once.

  2. 2

    Configure your MCP client

    Add the Crystal MCP server to your client. Use the server URL below, choose OAuth2 as the auth method, and enter the client ID and client secret you generated in step 1. For Claude and ChatGPT, see the dedicated walkthroughs below.

    MCP server URL

    https://mcp.crystalknows.com

    Configuration steps vary by client (for example Cursor or Claude Desktop). In general: add a new MCP server, set the URL above, select OAuth2, and paste your client ID and client secret. Crystal handles the OAuth callback automatically.

  3. 3

    Add Crystal as a custom connector in Claude

    Claude supports custom MCP connectors directly from claude.ai. To add Crystal:

    1. 1.Go to claude.ai/customize/connectors and click Add custom connector.
    2. 2.Set the Name to Crystal and the Remote MCP server URL to https://mcp.crystalknows.com.
    3. 3.Expand Advanced settings and paste the OAuth Client ID and OAuth Client Secret you generated in step 1.
    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.
  4. 4

    Add Crystal as a custom connector in ChatGPT

    Developer mode required

    ChatGPT only allows custom MCP connectors when Developer mode is enabled. Turn it on in Settings → Connectors → Advanced before continuing.

    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://mcp.crystalknows.com.
    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 step 1.
    4. 4.Copy the callback URL that ChatGPT shows you, then paste it into the Callback URLs field on the Crystal MCP server page and save.
    5. 5.Save the connector in ChatGPT, then connect and complete the Crystal OAuth flow when prompted.
  5. 5

    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 (e.g. “Search for a profile”, “Fetch my Personality Profile”).
    3. 3.Try a tool, for example use Fetch my Personality Profile or Search for a profile with an email, and confirm you get a response.

Reference

Tools reference

The Crystal MCP server exposes the following tools. All require OAuth2; no scopes are used. Click a tool name to copy it.

  • search

    Search for a profile

    Find a person’s Crystal profile by email or LinkedIn URL; returns DISC/MBTI/Enneagram + communication tips

    Parameters: query (email/LinkedIn URL or name), optional tags

  • fetch

    Fetch Profile from ID

    Get a full Crystal profile by Crystal Profile ID (use after search)

    Parameters: id

  • get_myself

    Fetch my Personality Profile

    Information to aid in communications to/from the current user and their coworkers

    Parameters: none

  • get_upcoming_meetings

    Get Upcoming Meetings

    List upcoming meetings and provide group communication guidance using attendees’ personalities

    Parameters: none

  • all_profile_tags

    All Profile Tags

    Lists all valid profile tags that have been used in the past

    Parameters: none

  • add_profile_tags

    Add Profile Tags

    Add tags to a profile for segmentation (e.g. prospect, customer, engineering)

    Parameters: id, tags (comma-separated)

  • remove_profile_tags

    Remove Profile Tags

    Remove tags from a profile

    Parameters: id, tags (comma-separated)

Troubleshooting

Common issues

  • OAuth fails or "redirect_uri_mismatch"

    Crystal pre-registers the standard MCP client callback URLs (Claude, ChatGPT, etc.) automatically when credentials are issued. If you’re using a non-standard client whose callback URL isn’t recognized, add it on the self-serve MCP server page or contact support.

  • Invalid client ID or secret

    Double-check that you pasted the client ID and client secret with no extra spaces. The secret is only shown once when generated, so if you lost it, generate a new pair on the self-serve page.

  • ChatGPT doesn’t show a "Create custom connector" option

    Custom connectors are only available with Developer mode enabled. Turn it on under Settings → Connectors → Advanced and reload the page.

  • Client does not support OAuth2 for MCP

    The Crystal MCP server requires OAuth2. Use an MCP client that supports OAuth2 (e.g. Claude, ChatGPT with Developer mode, Cursor, Claude Desktop with OAuth support).

  • Tools don’t appear after connecting

    Restart your MCP client after adding the server and completing the OAuth flow. If the client caches tool lists, trigger a refresh or reconnect.

In practice

Common use cases

Each use case below combines a few Crystal tools end-to-end. Try the example prompts in your MCP client to see them in action.

Meeting prep

Pull upcoming meetings, look up each attendee, and get tailored talking points before you walk in.

  • “Prep me for my 2pm tomorrow”
  • “How should I open the discussion with everyone in my next leadership sync?”

Cold outreach drafting

Look up a prospect by email or LinkedIn and draft an opener that matches their communication style.

  • “Draft a cold email to [email protected] — keep it in her style”
  • “Write a LinkedIn note to [profile URL] introducing our product”

Difficult conversations

Get a personality-aware approach for tough feedback, declining requests, or pushing back.

  • “I need to tell Brandon his proposal won’t work — how should I frame it?”
  • “Help me decline a meeting request from a high-D colleague without burning the relationship”

Negotiation strategy

Use someone’s DISC/MBTI to anticipate their negotiating style and prepare counter-moves.

  • “I’m negotiating renewal with this customer — what should I expect from her?”
  • “How do I close this deal with a Cs buyer?”

New hire onboarding

Build a “how to work with me” doc, or help managers understand a new report’s style fast.

  • “Summarize my profile as a one-pager I can share with my new team”
  • “How should I run 1:1s with my new hire [email]?”

Team dynamics & retros

Map a team’s personality mix to spot collaboration gaps or facilitation needs.

  • “Look up everyone tagged “engineering” and tell me what styles I should plan for in our offsite”
  • “Who on my team is most likely to clash with a high-D stakeholder?”

Customer segmentation with tags

Tag profiles by deal stage, persona, or account, then pull cohorts later.

  • “Tag everyone I met this week as “q2-pipeline””
  • “Show me everyone tagged “champion” across my accounts”

Personalized follow-ups

After a call or email exchange, draft a follow-up that matches the other person’s pace, detail level, and formality.

  • “Write a follow-up to Brian after our discovery call”
  • “Summarize next steps for [email protected] in her preferred style”

Pre-interview research

Look up a candidate before the interview and adjust your questioning approach.

  • “I’m interviewing [LinkedIn URL] tomorrow — how should I run the conversation?”

Self-awareness check-ins

Periodically revisit your own profile to spot blind spots before high-stakes situations.

  • “Remind me of my blind spots before I go into this board meeting”
  • “What drains me — am I about to walk into one of those situations?”

Support

Need help?

If you have questions or run into issues setting up the Crystal MCP server, reach out to your Customer Success Manager or contact our support team.

Contact Support

Bring personality intelligence into your AI tools

Connect Crystal to Claude, ChatGPT, Cursor, Windsurf, and any MCP-compatible client to look up profiles and communication guidance right where you work.

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