EventEmitter overflow (drain) when MCP server doesn't support resources/list #25078

Description

When using mcp-server-excel (or any MCP server that doesn't support
resources/list), OpenCode continuously polls resources/list and
accumulates drain listeners until EventEmitter overflow.

The author of mcp-server-excel confirmed this is an OpenCode-side bug:
sbroenne/mcp-server-excel#621

MCP client should handle -32601 (Method not available) without
accumulating listeners or crashing.

Suggested fix: add an option to disable resources/list polling for
servers that don't advertise resources.

Plugins

mcp-server-excel (sbroenne)

OpenCode version

1.14.30

Steps to reproduce

1. Install mcp-server-excel via dotnet tool:
   dotnet tool install --global Sbroenne.ExcelMcp.McpServer

2. Add the MCP to opencode.json:
   "excel-sbroenne": {
   "type": "local",
   "enabled": true,
   "command": ["mcp-excel"],
   "timeout": 60000
   }

3. Open OpenCode

4. Observe the EventEmitter overflow error on startup:
   MaxListenersExceededWarning: Possible EventEmitter memory leak detected.
   11 drain listeners added to [Socket]. MaxListeners is 10.
   type: "drain", count: 11

Screenshot and/or share link

Operating System

Windows 11

Terminal

Windows Terminal (PowerShell 7)