diff --git a/src/utils/security.ts b/src/utils/security.ts
index c6ecbc9..1a0e1d6 100644
--- a/src/utils/security.ts
+++ b/src/utils/security.ts
@@ -412,8 +412,13 @@ async function executeApiTool(
                 urlPath = urlPath.replace(\`{\${param.name}}\`, encodeURIComponent(String(value)));
             }
             else if (param.in === 'query') {
-                queryParams[param.name] = value;
-            }
+                // Convert arrays to comma-separated strings for query parameters
+                queryParams[param.name] = Array.isArray(value)
+                  ? value
+                      .filter((v) => v !== undefined && v !== null)
+                      .map((v) => String(v))
+                      .join(',')
+                  : value;            }
             else if (param.in === 'header') {
                 headers[param.name.toLowerCase()] = String(value);
             }