diff --git a/fern/openapi.json b/fern/openapi.json
index 4fa4a0fc..fdf98425 100644
--- a/fern/openapi.json
+++ b/fern/openapi.json
@@ -8718,19 +8718,26 @@
       "get": {
         "tags": ["conversations"],
         "summary": "List Conversations",
-        "description": "List all conversations for an agent.",
+        "description": "List all conversations for an agent (or all conversations if agent_id not provided).",
         "operationId": "list_conversations",
         "parameters": [
           {
             "name": "agent_id",
             "in": "query",
-            "required": true,
+            "required": false,
             "schema": {
-              "type": "string",
-              "description": "The agent ID to list conversations for",
+              "anyOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "The agent ID to list conversations for (optional - returns all conversations if not provided)",
               "title": "Agent Id"
             },
-            "description": "The agent ID to list conversations for"
+            "description": "The agent ID to list conversations for (optional - returns all conversations if not provided)"
           },
           {
             "name": "limit",
diff --git a/letta/server/rest_api/routers/v1/conversations.py b/letta/server/rest_api/routers/v1/conversations.py
index c0d691ca..fef31b06 100644
--- a/letta/server/rest_api/routers/v1/conversations.py
+++ b/letta/server/rest_api/routers/v1/conversations.py
@@ -60,14 +60,14 @@ async def create_conversation(
 
 @router.get("/", response_model=List[Conversation], operation_id="list_conversations")
 async def list_conversations(
-    agent_id: str = Query(..., description="The agent ID to list conversations for"),
+    agent_id: Optional[str] = Query(None, description="The agent ID to list conversations for (optional - returns all conversations if not provided)"),
     limit: int = Query(50, description="Maximum number of conversations to return"),
     after: Optional[str] = Query(None, description="Cursor for pagination (conversation ID)"),
     summary_search: Optional[str] = Query(None, description="Search for text within conversation summaries"),
     server: SyncServer = Depends(get_letta_server),
     headers: HeaderParams = Depends(get_headers),
 ):
-    """List all conversations for an agent."""
+    """List all conversations for an agent (or all conversations if agent_id not provided)."""
     actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
     return await conversation_manager.list_conversations(
         agent_id=agent_id,
diff --git a/letta/services/conversation_manager.py b/letta/services/conversation_manager.py
index 9c709ae5..7d374092 100644
--- a/letta/services/conversation_manager.py
+++ b/letta/services/conversation_manager.py
@@ -103,16 +103,16 @@ class ConversationManager:
     @trace_method
     async def list_conversations(
         self,
-        agent_id: str,
+        agent_id: Optional[str],
         actor: PydanticUser,
         limit: int = 50,
         after: Optional[str] = None,
         summary_search: Optional[str] = None,
     ) -> List[PydanticConversation]:
-        """List conversations for an agent with cursor-based pagination.
+        """List conversations for an agent (or all conversations) with cursor-based pagination.
 
         Args:
-            agent_id: The agent ID to list conversations for
+            agent_id: The agent ID to list conversations for (optional - returns all if not provided)
             actor: The user performing the action
             limit: Maximum number of conversations to return
             after: Cursor for pagination (conversation ID)
@@ -126,16 +126,20 @@ class ConversationManager:
             if summary_search:
                 from sqlalchemy import and_
 
+                # Build where conditions
+                conditions = [
+                    ConversationModel.organization_id == actor.organization_id,
+                    ConversationModel.summary.isnot(None),
+                    ConversationModel.summary.contains(summary_search),
+                ]
+                
+                # Add agent_id filter if provided
+                if agent_id is not None:
+                    conditions.append(ConversationModel.agent_id == agent_id)
+
                 stmt = (
                     select(ConversationModel)
-                    .where(
-                        and_(
-                            ConversationModel.agent_id == agent_id,
-                            ConversationModel.organization_id == actor.organization_id,
-                            ConversationModel.summary.isnot(None),
-                            ConversationModel.summary.contains(summary_search),
-                        )
-                    )
+                    .where(and_(*conditions))
                     .order_by(ConversationModel.created_at.desc())
                     .limit(limit)
                 )