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Use ChatGPT with Spectral MCP

Connect ChatGPT to Spectral through the Spectral MCP server to create structural models and add model elements from a chat.

Spectral uses OAuth authorization code with PKCE. Do not paste private credentials or deployment secrets into ChatGPT.

Requirements​

  • Access to ChatGPT Developer Mode.
  • A Spectral account that can sign in through https://auth.spectralco.co.
  • Network access from ChatGPT to https://mcp.spectralco.co/mcp.
  • Permission to grant these Spectral MCP scopes:
    • mcp:models:read
    • mcp:models:write
info

The Spectral MCP endpoint is hosted over Streamable HTTP. You do not need to run a local MCP server for ChatGPT Developer Mode.

Setup​

Step 1: Turn on ChatGPT Developer Mode​

  1. Open ChatGPT.
  2. Open Settings.
  3. Go to Apps.
  4. Open Advanced settings.
  5. Turn on Developer Mode.

Developer Mode can expose tools that change data. Keep it enabled only in workspaces where you are comfortable reviewing tool calls before they run.

Step 2: Add the Spectral MCP server​

In ChatGPT Developer Mode, add a custom app or MCP connector with these values:

{
  "name": "Spectral",
  "mcp_server_url": "https://mcp.spectralco.co/mcp",
  "transport": "streaming_http",
  "authentication": "oauth",
  "scopes": "mcp:models:read mcp:models:write"
}

If the setup screen asks for OAuth metadata, use:

FieldValue
MCP server URLhttps://mcp.spectralco.co/mcp
OAuth issuerhttps://auth.spectralco.co
Authorization endpointhttps://auth.spectralco.co/oauth/authorize
Token endpointhttps://auth.spectralco.co/oauth/token
Dynamic client registrationhttps://auth.spectralco.co/oauth/register
Resourcehttps://mcp.spectralco.co/mcp
Scopesmcp:models:read mcp:models:write

Step 3: Sign in and approve access​

ChatGPT opens the Spectral OAuth authorization page.

  1. Sign in with your Spectral account.
  2. Review the requested scopes.
  3. Approve access only if the app name, resource, and scopes match the values above.
  4. Return to ChatGPT and enable the Spectral app for the chat.

Step 4: Test model creation​

Use a small test prompt:

Use Spectral to create an empty model named ChatGPT MCP Smoke Test.

Review the proposed tool call before approving it. Write tools can create or change Spectral model data.

What ChatGPT Can Access​

With the approved scopes, ChatGPT can ask Spectral to:

  • Create a new model owned by your Spectral account.
  • Add structural elements to a model you can write to.
  • Return a viewer payload or viewer URL for the created model.

Example Prompts​

WorkflowPrompt
Create a draft modelCreate a new Spectral model named "Concept Grid A" and tell me the viewer link.
Add elementsAdd a small three-bay frame to my test model. Ask before running any write tool.
Create from JSONCreate a Spectral model from this nodes-and-frames JSON payload and show the planned arguments first.

Privacy And Data Handling​

  • ChatGPT receives only the Spectral data returned by the MCP tools you ask it to use.
  • OAuth credentials are scoped to the approved resource and scopes.
  • Model names, element payloads, viewer payloads, and prompts may be visible in the chat where you use the connector.
  • Write tools can change model data. Review proposed tool calls before approving them.

Disconnect Or Remove Spectral​

To stop using Spectral in ChatGPT, open ChatGPT settings and remove or disable the Spectral app or connector.

Troubleshooting​

I do not see Developer Mode​

Developer Mode may not be available for your plan or workspace. Ask the workspace owner to confirm app and Developer Mode settings.

OAuth does not open or fails​

Allow popups for ChatGPT and try again. Confirm the MCP endpoint is exactly https://mcp.spectralco.co/mcp and that the OAuth issuer is https://auth.spectralco.co.

The connection succeeds but no tools appear​

Refresh the Developer Mode app. If tool descriptions, output schemas, resources, or widget metadata changed recently, ChatGPT may need the draft app to be reloaded.

A write action is blocked or asks for confirmation​

That is expected. Spectral write tools can create models or add model elements, so ChatGPT should ask you to review the action before it runs.

GET /mcp returns 405​

That is expected for the current Streamable HTTP deployment. The MCP endpoint accepts protocol requests over POST /mcp.

Access expires​

Reconnect the Spectral app in ChatGPT and complete OAuth again.

Help And Next Steps​

  • For MCP concepts and shared troubleshooting, see /docs/mcp/overview and /docs/mcp/troubleshooting.
  • For Spectral authentication details, see /docs/mcp/authentication.
  • If setup still fails, contact Spectral support with the ChatGPT workspace type, approximate connection time, MCP endpoint used, and the failing step.