The biggest disappointment I have with MCP today is that many clients are still half-assed on supporting the functions outside of MCP tools.

Namely, two very useful features resources and prompts have varying levels of support across clients (Codex being one of the worst).

These two are possibly the most powerful ones since they allow consistent, org-level remote delivery of context and I would like to see all major clients support these two and eventually catch up on the other features like elicitation, progress, tasks, etc.