fix: show descriptive MCP server connection errors instead of generic 500s #3256
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What does this PR do?
Fixes error handling when MCP server connections fail. Instead of returning generic 500 errors, now provides
descriptive error messages with proper HTTP status codes.
Closes #3107
Test Plan
Before fix:
curl -X GET "http://localhost:8321/v1/tool-runtime/list-tools?tool_group_id=bad-mcp-server"
Returns: {"detail": "Internal server error: An unexpected error occurred."} (500)
After fix:
curl -X GET "http://localhost:8321/v1/tool-runtime/list-tools?tool_group_id=bad-mcp-server"
Returns: {"error": {"detail": "Failed to connect to MCP server at http://localhost:9999/sse: Connection
refused"}} (502)
Tests: