“screenshots_not_allowed”

Screenshots were attached, and the current tool scan reports no tool with a UI output template. The three common causes: (1) No tool links a view: the UI exists as a resource but nothing points at it. To tell: The doctor's verdict is no_ui, or it fails at tool-no-ui. (2) The scan is older than the UI: it was added after the last Scan Tools. To tell: The doctor's screenshots line says the scan will report a UI template; rescan in the portal. (3) The UI is registered only for clients that declare MCP Apps support, and the scan did not see it. To tell: The doctor (which declares support) finds the UI; the portal does not. One command shows which: npx --allow-git=root github:agentwares/mcp-apps-doctor https://your-server.example/mcp --host chatgpt-directory.

Check your server now

npx --allow-git=root github:agentwares/mcp-apps-doctor https://your-server.example/mcp --host chatgpt-directory

Discovery only: no credential, no tool called. It prints the first broken step, whose it is, and the fix with its source, and shows the view in a sandboxed preview.

Who prints it

OpenAI's plugin submission portal, when screenshots are attached to a plugin whose scan found no UI.

The three causes, and how to tell them apart

1. Cause 1. No tool links a view: the UI exists as a resource but nothing points at it.
   The check flags it at tool-no-ui. The doctor's verdict is no_ui, or it fails at tool-no-ui.
2. Cause 2. The scan is older than the UI: it was added after the last Scan Tools.
   The check cannot see this one from outside: it happens inside the host or the portal. The doctor's screenshots line says the scan will report a UI template; rescan in the portal.
3. Cause 3. The UI is registered only for clients that declare MCP Apps support, and the scan did not see it.
   The check cannot see this one from outside: it happens inside the host or the portal. The doctor (which declares support) finds the UI; the portal does not.

Sources and public reports

• screenshots_not_allowed; screenshots are one per starter prompt, 706 px wide, 400–860 px tall [source: OpenAI plugin submission errors, read 8 October 2026]

Keep checking

agentcheck's free watch checks this server every hour and emails when it stops answering or its tool list changes; no account. It does not re-read the ui:// views.

mcpcheck Server Pro diffs the server's tool catalog every night — removed tools, tightened schemas, changed descriptions — with the client-compat matrix, OAuth conformance and 90 days of history; $49 a server a month, first run free. It does not re-run these MCP Apps checks.

Other messages

• “MCP App renders blank”
• “Resource not found: ui://”
• “Tool has no UI”
• “Invalid ui.domain format”
• “ui.domain mismatch”
• “Refused to load the script”
• “annotations_required”
• “domain_verification_required”
• “frame_domain_explanation_required”
• “Failed to fetch template”

Written 8 October 2026 from the sources above. The MCP Apps check · MCP Liveness · Terms · Privacy