fix: use ?? to prevent args being undefined for mcp server in some cases (#11203)

packages/opencode/src/mcp/index.ts

@@ -135,7 +135,7 @@ export namespace MCP {
         return client.callTool(
           {
             name: mcpTool.name,
-            arguments: args as Record<string, unknown>,
+            arguments: (args || {}) as Record<string, unknown>,
           },
           CallToolResultSchema,
           {