diff --git a/GB_is_save_state.md b/GB_is_save_state.md
index 1dc63ae..051a2f7 100644
--- a/GB_is_save_state.md
+++ b/GB_is_save_state.md
@@ -6,8 +6,17 @@ In `save_state.h`
 
 ## Description
 
-TBD
+Returns `true` if the file at `path` contains a SameBoy or [BESS](https://github.com/LIJI32/SameBoy/blob/master/BESS.md) save state. 
 
 ## Thread Safety
 
 `GB_is_save_state` is thread-safe and can be called from any thread and context.
+
+## Notes
+
+This function merely checks for header and footer magic values, it does not guarantee the file will successfully load with [[GB_load_state]], etc.
+
+## See Also
+
+* [[GB_get_state_model]]
+* [[GB_get_state_model_from_buffer]]
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