diff --git a/agents.md b/agents.md
index 8b305cbdb1..fb45f71dde 100644
--- a/agents.md
+++ b/agents.md
@@ -184,7 +184,7 @@ class RetrieverTool(Tool):
     }
     output_type = "text"
     
-    def __init__(self, vectordb: VectorStore, all_sources: str, **kwargs):
+    def __init__(self, vectordb: VectorStore, all_sources: list[str], **kwargs):
         super().__init__(**kwargs)
         self.vectordb = vectordb
         self.inputs["source"]["description"] = (
@@ -450,4 +450,4 @@ We will keep improving this package in the coming months. We have already identi
 
 👉 **Go try out transformers agents!** We’re looking forward to receiving your feedback and your ideas.
 
-Let’s fill the top of the leaderboard with more open-source models! 🚀
\ No newline at end of file
+Let’s fill the top of the leaderboard with more open-source models! 🚀