diff --git a/crates/cargo-util-schemas/index.schema.json b/crates/cargo-util-schemas/index.schema.json
index 8901dc4718c..189ee19fd83 100644
--- a/crates/cargo-util-schemas/index.schema.json
+++ b/crates/cargo-util-schemas/index.schema.json
@@ -69,7 +69,7 @@
       ]
     },
     "pubtime": {
-      "description": "The publish time for the package.  Unstable.\n\nIn ISO8601 with UTC timezone (e.g. 2025-11-12T19:30:12Z)\n\nThis should be the original publish time and not changed on any status changes,\nlike [`IndexPackage::yanked`].",
+      "description": "The publish time of this package version (optional).\n\nThe format is a subset of ISO8601:\n- `yyyy-mm-ddThh:mm:ssZ`\n- no fractional seconds\n- always `Z` for UTC timezone, no timezone offsets supported\n- fields are 0-padded\n\nExample: 2025-11-12T19:30:12Z\n\nThis should be the original publish time and not changed on any status changes,\nlike [`IndexPackage::yanked`].",
       "type": [
         "string",
         "null"
diff --git a/crates/cargo-util-schemas/src/index.rs b/crates/cargo-util-schemas/src/index.rs
index 0b029ce15ab..5f58dfadb7c 100644
--- a/crates/cargo-util-schemas/src/index.rs
+++ b/crates/cargo-util-schemas/src/index.rs
@@ -46,9 +46,15 @@ pub struct IndexPackage<'a> {
     /// can be `None` if published before then or if not set in the manifest.
     #[cfg_attr(feature = "unstable-schema", schemars(with = "Option<String>"))]
     pub rust_version: Option<RustVersion>,
-    /// The publish time for the package.  Unstable.
+    /// The publish time of this package version (optional).
     ///
-    /// In ISO8601 with UTC timezone (e.g. 2025-11-12T19:30:12Z)
+    /// The format is a subset of ISO8601:
+    /// - `yyyy-mm-ddThh:mm:ssZ`
+    /// - no fractional seconds
+    /// - always `Z` for UTC timezone, no timezone offsets supported
+    /// - fields are 0-padded
+    ///
+    /// Example: 2025-11-12T19:30:12Z
     ///
     /// This should be the original publish time and not changed on any status changes,
     /// like [`IndexPackage::yanked`].
diff --git a/src/doc/src/reference/registry-index.md b/src/doc/src/reference/registry-index.md
index dbb7638b8bb..f982b557237 100644
--- a/src/doc/src/reference/registry-index.md
+++ b/src/doc/src/reference/registry-index.md
@@ -218,7 +218,20 @@ explaining the format of the entry.
     }
     // The minimal supported Rust version (optional)
     // This must be a valid version requirement without an operator (e.g. no `=`)
-    "rust_version": "1.60"
+    "rust_version": "1.60",
+    // The publish time of this package version (optional).
+    //
+    // The format is a subset of ISO8601:
+    // - `yyyy-mm-ddThh:mm:ssZ`
+    // - no fractional seconds
+    // - always `Z` for UTC timezone, no timezone offsets supported
+    // - fields are 0-padded
+    //
+    // Example: 2025-11-12T19:30:12Z
+    //
+    // This should be the original publish time and not changed on any status changes,
+    // like `yanked`.
+    "pubtime": "2025-11-12T19:30:12Z"
 }
 ```
 
diff --git a/src/doc/src/reference/unstable.md b/src/doc/src/reference/unstable.md
index 71d674b0975..a24123a8d9c 100644
--- a/src/doc/src/reference/unstable.md
+++ b/src/doc/src/reference/unstable.md
@@ -1843,14 +1843,6 @@ Specify which packages participate in [feature unification](../reference/feature
 * `package`: Dependency features are considered on a package-by-package basis,
   preferring duplicate builds of dependencies when different sets of features are activated by the packages.
 
-## pubtime
-
-* Original Issue: [#15491](https://github.com/rust-lang/cargo/issues/15491)
-* Tracking Issue: [#16270](https://github.com/rust-lang/cargo/issues/16270)
-
-Documentation updates:
-- Add `pubtime` field to the Index Summary description
-
 ## lockfile-publish-time
 
 * Original Issue: [#5221](https://github.com/rust-lang/cargo/issues/5221)
@@ -2273,3 +2265,7 @@ See <https://github.com/rust-lang/cargo/issues/7614> for the reason for its remo
 Support for including extra configuration files via the `include` config key
 has been stabilized in 1.93.0.
 See the [`include` config documentation](config.md#include) for more.
+
+## pubtime
+
+The `pubtime` index field  has been stabilized in Rust 1.94.0.