Summary

Implement support for MCP Apps — the official MCP extension (spec version 2026-01-26) that enables tools to return interactive UI components rendered in sandboxed iframes by MCP hosts.

This will allow the kubernetes-mcp-server to provide rich, interactive experiences such as:

• Interactive resource tables with sorting, filtering, and actions
• Visual dashboards for cluster metrics and status
• Forms for resource creation/editing
• Topology visualizations for workloads and networking

This is an opt-in feature, disabled by default, controlled by the apps_enabled configuration flag / --apps CLI flag.

Background

MCP Apps extend the Model Context Protocol by letting tools declare UI resources:

1. Tool definition — Tools declare a _meta.ui.resourceUri field pointing to a ui:// resource
2. Tool call — LLM invokes the tool on the server
3. Host renders — Host fetches the HTML resource via resources/read and displays it in a sandboxed iframe
4. Bidirectional communication — Host passes tool data via postMessage notifications; UI can call other server tools via JSON-RPC over postMessage

Supported hosts: VS Code (Insiders + Stable), Claude (web/desktop), ChatGPT, Goose, Postman, MCPJam.

References

• Specification: https://modelcontextprotocol.github.io/ext-apps/api/
• Official blog post: https://blog.modelcontextprotocol.io/posts/2026-01-26-mcp-apps/
• SDK & Examples: https://github.com/modelcontextprotocol/ext-apps
• Go-SDK extensions support (merged, in v1.4.0):
  • Extension declaration for MCP Apps modelcontextprotocol/go-sdk#777
  • mcp: add Extensions field to capabilities per SEP-2133 modelcontextprotocol/go-sdk#794
• PoC reference: OLS-2568: Add mcp app pods top UI openshift/openshift-mcp-server#143

Research and Implementation Plan

Detailed research document with all findings, architectural decisions, and implementation guidance:
docs/mcp-apps-research.md (on branch feat/mcp-apps)

Key decisions

Acceptance Criteria

• Feature is opt-in via apps_enabled config / --apps flag (disabled by default)
• At least one tool demonstrates full MCP Apps integration with interactive UI
• Works with VS Code Copilot and other MCP Apps-compatible hosts
• Zero behavioral change when apps_enabled = false
• No build step required (no Node.js/npm dependency)
• Compatible with airgapped environments (vendored JS)
• Documentation for the feature and configuration