diff --git a/src/mcp-server.ts b/src/mcp-server.ts
index 6732a97..20070d2 100644
--- a/src/mcp-server.ts
+++ b/src/mcp-server.ts
@@ -153,7 +153,7 @@ async function main() {
       outputSchema: evaluateOutputSchema,
       annotations: {
         readOnlyHint: true,
-        idempotentHint: false,
+        idempotentHint: true,
         openWorldHint: false,
       },
     },