diff --git a/src/agents/tools/message-tool.ts b/src/agents/tools/message-tool.ts
index 44618cbede..277f5f083d 100644
--- a/src/agents/tools/message-tool.ts
+++ b/src/agents/tools/message-tool.ts
@@ -413,7 +413,7 @@ export function createMessageTool(options?: MessageToolOptions): AnyAgentTool {
       // in tool arguments, and the messaging tool send path has no other tag filtering.
       for (const field of ["text", "content", "message", "caption"]) {
         if (typeof params[field] === "string") {
-          params[field] = stripReasoningTagsFromText(params[field] as string);
+          params[field] = stripReasoningTagsFromText(params[field]);
         }
       }