Give Some Sort of Message When a Configured MCP Server Isn't Working

[MRayermannMSFT]

Describe the feature or problem you'd like to solve

When configuring a new MCP server, I might make a mistake. Currently this can be hard to detect, as the process for configuring a new server gives no feedback on if the configuration was/is working.

Proposed solution

Two ideas:

1. Immediately test the configuration in the MCP add/edit UX, and inform the user if the test fails.
2. Give a message in timeline in the when a configured MCP server doesn't work (the CLI wasn't able to get tools from the server).

Example prompts or workflows

No response

Additional context

No response

[examon]

This is now supported. When a configured MCP server fails to connect, the CLI surfaces a warning in the session timeline directing you to run /mcp show <server-name> for inspection. If you believe this isn't resolved, please feel free to reopen this issue.