diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index aa822b1f923..17342cacd76 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -483,7 +483,7 @@ impl<T> Vec<T> {
         Self::with_capacity_in(capacity, Global)
     }
 
-    /// Creates a `Vec<T>` directly from the raw components of another vector.
+    /// Creates a `Vec<T>` directly from a pointer, a capacity, and a length.
     ///
     /// # Safety
     ///
@@ -498,12 +498,14 @@ impl<T> Vec<T> {
     ///   to be the same size as the pointer was allocated with. (Because similar to
     ///   alignment, [`dealloc`] must be called with the same layout `size`.)
     /// * `length` needs to be less than or equal to `capacity`.
+    /// * The first `length` values must be properly initialized values of type `T`.
     /// * `capacity` needs to be the capacity that the pointer was allocated with.
-    /// * The allocated size in bytes must be no larger than  `isize::MAX`.
+    /// * The allocated size in bytes must be no larger than `isize::MAX`.
     ///   See the safety documentation of [`pointer::offset`].
     ///
-    /// To ensure these requirements are easily met, ensure `ptr` has previously
-    /// been allocated via `Vec<T>`.
+    /// These requirements are always uphead by any `ptr` that has been allocated
+    /// via `Vec<T>`. Other allocation sources are allowed if the invariants are
+    /// upheld.
     ///
     /// Violating these may cause problems like corrupting the allocator's
     /// internal data structures. For example it is normally **not** safe
@@ -645,7 +647,8 @@ impl<T, A: Allocator> Vec<T, A> {
         Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 }
     }
 
-    /// Creates a `Vec<T, A>` directly from the raw components of another vector.
+    /// Creates a `Vec<T, A>` directly from a pointer, a capacity, a length,
+    /// and an allocator.
     ///
     /// # Safety
     ///
@@ -660,12 +663,14 @@ impl<T, A: Allocator> Vec<T, A> {
     ///   to be the same size as the pointer was allocated with. (Because similar to
     ///   alignment, [`dealloc`] must be called with the same layout `size`.)
     /// * `length` needs to be less than or equal to `capacity`.
-    /// * `capacity` needs to be the capacity that the pointer was allocated with.
-    /// * The allocated size in bytes must be no larger than  `isize::MAX`.
+    /// * The first `length` values must be properly initialized values of type `T`.
+    /// * `capacity` needs to [fit] the layout size that the pointer was allocated with.
+    /// * The allocated size in bytes must be no larger than `isize::MAX`.
     ///   See the safety documentation of [`pointer::offset`].
     ///
-    /// To ensure these requirements are easily met, ensure `ptr` has previously
-    /// been allocated via `Vec<T>`.
+    /// These requirements are always uphead by any `ptr` that has been allocated
+    /// via `Vec<T>`. Other allocation sources are allowed if the invariants are
+    /// upheld.
     ///
     /// Violating these may cause problems like corrupting the allocator's
     /// internal data structures. For example it is **not** safe
@@ -683,6 +688,7 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// [`String`]: crate::string::String
     /// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc
+    /// [*fit*]: crate::alloc::Allocator#memory-fitting
     ///
     /// # Examples
     ///