diff --git a/prompts/SYSTEM_PROMPT.md b/prompts/SYSTEM_PROMPT.md
index 4672fdf..ce64806 100644
--- a/prompts/SYSTEM_PROMPT.md
+++ b/prompts/SYSTEM_PROMPT.md
@@ -4,6 +4,9 @@
 - Platform: ${PRIME_PLATFORM}
 - Current date: ${PRIME_DATE}
 - Is git repo: ${PRIME_IS_GIT_REPO}
+- Sandbox: ${PRIME_SANDBOX}
+
+Tools run in a sandbox with restricted filesystem access. Unexpected permission denied errors are usually caused by sandbox restrictions. Use `elevated: true` to bypass.
 
 # Core Identity