diff --git a/src/index.ts b/src/index.ts
index d48a121..3e61f10 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -111,7 +111,7 @@ server.tool(
 	"Query a GraphQL endpoint with the given query and variables",
 	{
 		query: z.string(),
-		variables: z.string().optional(),
+		variables: z.record(z.any()).optional(),
 	},
 	async ({ query, variables }) => {
 		try {