diff --git a/requirements.txt b/requirements.txt
index 8a4c5b9..f782d22 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
 ydb>=3.21.0
-mcp>=1.6.0
\ No newline at end of file
+mcp==1.12.4
diff --git a/ydb_mcp/server.py b/ydb_mcp/server.py
index 8426b1a..97137a4 100644
--- a/ydb_mcp/server.py
+++ b/ydb_mcp/server.py
@@ -536,7 +536,15 @@ def register_tools(self):
 
         # Register all tools with FastMCP framework
         for spec in tool_specs:
-            self.add_tool(spec["handler"], name=spec["name"], description=spec["description"])
+            self.add_tool(
+                spec["handler"],
+                name=spec["name"],
+                description=spec["description"],
+
+                # Structured output is temporarily disabled until proper schema definitions are implemented.
+                # See https://github.com/ydb-platform/ydb-mcp/issues/12 for details.
+                structured_output=False,
+            )
 
             # Also register with our tool manager
             self.tool_manager.register_tool(