Add a server-side option to completely disable MCP Apps #3488

Describe the feature or problem you’d like to solve

Add a server-side option to completely disable MCP Apps.

Currently, --features=mcp_apps_disable_form_deferral prevents write tools from being deferred to interactive forms, but MCP Apps are still enabled and UI metadata/resources are still exposed.

This means the MCP App UI can still open after the operation. This can interrupt the agent workflow and require additional UI interaction even though the underlying write has already been applied.

What is missing is an option to disable MCP Apps entirely at the server level.

Proposed solution

Add an option such as:

--mcp-apps=false

and/or:

GITHUB_MCP_APPS=false

When disabled, the server should:

• not expose MCP Apps UI metadata/resources
• not use form deferral
• execute tools normally and return inline results

The default can remain enabled, so this would be fully backwards compatible.

This would complement, not replace --features=mcp_apps_disable_form_deferral

Example prompts or workflows (for tools/toolsets only)

Not applicable. This is a server configuration option rather than a new tool.

Additional context

I use the same GitHub MCP Docker image from multiple MCP clients, each with different ways of enabling or disabling MCP Apps.

A server-side opt-out would provide one deterministic configuration for Docker/headless deployments instead of requiring client-specific workarounds.