diff --git a/index.d.ts b/index.d.ts
index 3a09336..c6392d0 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -101,9 +101,10 @@ declare namespace WebMCP {
          */
         description: string;
         /**
-         * A stringified JSON Schema object describing the expected input parameters for the tool.
+         * A JSON Schema object describing the expected input parameters for the tool.
+         * It is a deep copy of the schema provided at tool registration, via `ModelContextTool.inputSchema`.
          */
-        inputSchema?: string;
+        inputSchema?: object;
         /**
          * The Window of the document that registered the tool.
          */