Update read.py

Author: beacoder

python_agent_harness/tools/read.py

@@ -18,6 +18,7 @@
 
 class Read(Tool):
     name = "Read"
+    is_readonly = True
     description = (
         "Read file contents between specified line numbers `start_line` and "
         "`end_line`, with both ends included.\n\n"