[FEATURE] Need a canonical way for MCP servers (e.g from plugins) to provide startup error messages

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Right now, when an MPC server fails to start, /mcp server listing just says ✘ failed and even when going into the detailed menu for that server, it only shows Status: ✘ failed with no further information (short of claude --debug - not very user friendly).

Proposed Solution

Include a detailed message. E.g "Status: ✘ failed: stderr message: ..." "Status: ✘ failed: MCP error -32603: ...", etc.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

MCP server integration

Use Case Example

mcp-atlassian does not start when the required environment variables are not present. Would be very helpful to have the actual error message included.

For my use case, I tried:

• Print to stderr + exit 1. Debug log: [ERROR] MCP server "plugin:[...]" Server stderr: .... UI: Status: ✘ failed
• Return error code in response to "initialize" command. Debug log: [DEBUG] MCP server "plugin:[...]": Connection failed after 120ms: MCP error -32603: .... UI: Status: ✘ failed

Additional Context

_No response_