Solved

Trouble connecting Lucid MCP with Claude AI: Error connecting to the MCP server

Forum|Forum|29 days ago
January 6, 2026
5 replies
114 views

StillView

I have tried connecting Claude AI web and desktop to the Lucid MCP and I can’t seem to get it all of the way there. It looks like I can get through part of the authorization process and the Lucid server responds back to Anthropic, but the final connections never get made. I wonder if anyone else has made it all of the way yet. Is there still more work to do on the Lucid side?
According to “Fin”, Claude’s AI help desk:

The most common cause is missing callback URLs in your OAuth provider settings. Make sure you've allowlisted both:

- https://claude.ai/api/mcp/auth_callback

- https://claude.com/api/mcp/auth_callback

Best answer by alison cheney

Hi @StillView,

Thank you for your response in the community and for providing such a detailed response to help us take a closer look!

I’ve consulted with our MCP engineering team, and they’ve provided some specific insights into how this connection works.

Regarding whitelisting the callback URLs and inputting Client ID into the developer portal: The Lucid MCP server uses Dynamic Client Registration (DCR), so these will both be handled automatically between Claude and Lucid. This means you don’t need to manually whitelist URLs or configure anything in the Lucid Developer Portal. My apologies for the confusion there!
Regarding the screens: After the first time, it is expected that you will not see the second consent screen that lists all the permissions/access. Your experience of the screens that you provided detailed screenshots for is expected.

Let’s try these steps next:

Try to turn off/on again: Navigate to the url https://lucid.app/user#/appsAndIntegrations/lucidchart. Next to 'Lucid MCP Server', click the tri-dot menu and select 'Disconnect application'. This will ensure you'll go through the full connection flow again when you connect to the MCP server. Try the connection again.

Verify the server URL: In your screenshot of the Custom Connector setup, I noticed the URL was entered as https://mcp.lucid.app/mc. Please ensure the full URL is used: https://mcp.lucid.app/mcp

If the issue persists after the above steps, please provide the following information so our engineering team can take a closer look:

Check for any error logs in Claude's logs. Instructions for viewing the log file in Claude Desktop can be found here. Can you please provide me with any error logs you see here? Once we have any relevant log details, I can have our engineers take a closer look.

Thank you for working through this with us!

alison cheney
Lucid community team
Forum|Forum|26 days ago
January 9, 2026

Hi @StillView,

Thank you for posting in the Lucid Community!

To clarify, I wanted to ask a few questions so I can take a closer look at the issue you’re experiencing:

What specific error message or status code appears in the Claude UI after the redirect? Could you send a screenshot of this specific error?
Since you mentioned trying both web and desktop, are you configuring the desktop app via Settings --> Connectors in the UI?
Can you confirm you've allowlisted both the .ai and the .com callback URLs in the Lucid developer portal?
When you added the connector, did you use the 'Advanced Settings' to manually input a Client ID and Secret from Lucid, or are you relying on the server to handle registration automatically (DCR)?
Are you using the official Lucid MCP URL https://mcp.lucid.app/mcp in the 'Connectors' settings, and does it fail after you see a 'Success' message from Lucid?

Here is this help center article with more information on integrating Lucid with AI tools using the Lucid MCP server. Here are specific resources to learn more about Claude Web and Claude Desktop. Thank you for your engagement in our community!

StillView
Author
Forum|Forum|26 days ago
January 9, 2026

Hi @alison cheney
1. Specific Error message is this

as an admin in Claude, when I try to connect to the Lucid MCP I have to set it up as a Custom Connector because you don’t show up directly in the marketplace. So I click here:
Then I get this simple screen and enter the following and set nothing in OAUTH. I assume SSO will take care of the connection for each individual when they do the connection. Once I hit add nothing special happens except that is now an option for users in there own claude Connectors
As a user in Claude I click connect
I get this screen and I click Authorize Claude

The very first time I did this I got the next screen and then never again. Every subsequent time I’ve tried it only get the above screen, and in all cases it ends in the error shown at the top.
You Asked “Can you confirm you've allowlisted both the .ai and the .com callback URLs in the Lucid developer portal?” → I’m a Lucid Admin but I don’t see where I have any control in Lucid over allow listing URLs, and the documentation doesn’t show me where I would have this control. which menu path would this control be in in the developer portal?
In the marketplace I do see this which makes me think it is available.

alison cheney
Lucid community team
Answer
Forum|Forum|23 days ago
January 12, 2026

Hi @StillView,

Thank you for your response in the community and for providing such a detailed response to help us take a closer look!

I’ve consulted with our MCP engineering team, and they’ve provided some specific insights into how this connection works.

Regarding whitelisting the callback URLs and inputting Client ID into the developer portal: The Lucid MCP server uses Dynamic Client Registration (DCR), so these will both be handled automatically between Claude and Lucid. This means you don’t need to manually whitelist URLs or configure anything in the Lucid Developer Portal. My apologies for the confusion there!
Regarding the screens: After the first time, it is expected that you will not see the second consent screen that lists all the permissions/access. Your experience of the screens that you provided detailed screenshots for is expected.

Let’s try these steps next:

Try to turn off/on again: Navigate to the url https://lucid.app/user#/appsAndIntegrations/lucidchart. Next to 'Lucid MCP Server', click the tri-dot menu and select 'Disconnect application'. This will ensure you'll go through the full connection flow again when you connect to the MCP server. Try the connection again.

Verify the server URL: In your screenshot of the Custom Connector setup, I noticed the URL was entered as https://mcp.lucid.app/mc. Please ensure the full URL is used: https://mcp.lucid.app/mcp

If the issue persists after the above steps, please provide the following information so our engineering team can take a closer look:

Check for any error logs in Claude's logs. Instructions for viewing the log file in Claude Desktop can be found here. Can you please provide me with any error logs you see here? Once we have any relevant log details, I can have our engineers take a closer look.

Thank you for working through this with us!

StillView
Author
Forum|Forum|8 days ago
January 27, 2026

@alison cheney I missed the note on your latest response here. THANK YOU for the response and both suggestions were helpful in resolving this! Even though I looked at the link 100 times I kept missing the obvious omission.

alison cheney
Lucid community team
Forum|Forum|6 days ago
January 29, 2026

@StillView, Thank you for your response! I’m happy to hear that it was resolved! Please don't hesitate to let me know if there is anything else I can do for you. Have a great rest of your day.

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