Apps configuration

Apps resources must use ui://, return the exact text/html;profile=mcp-app MIME type, and contain a complete HTML document as text or base64 blob. A referenced UI resource must be registered.

Tool metadata uses nested _meta.ui.resourceUri. By default the adapter also emits the deprecated flat ui/resourceUri key for compatibility with the official 1.7.5 helper. Tool visibility may include model, app, or both; use app-only visibility for mutations that should not be selected directly by a model.

Resource _meta.ui can declare:

• csp.connectDomains and csp.resourceDomains;
• permissions supported by the selected Apps codec;
• a dedicated application domain;
• prefersBorder for host presentation.

Listing metadata is static. resources/read may return content-specific metadata, which takes precedence as a whole value. A controlled generic metadata escape hatch is available, but selected stable or draft codecs still validate Apps fields.

Keep remote origins out of CSP unless required, expose no credentials or filesystem paths, and never assume declaration validation replaces host sandboxing or user approval.