diff --git a/crates/uv-cli/src/lib.rs b/crates/uv-cli/src/lib.rs
index 68d8a4d0d..f88334471 100644
--- a/crates/uv-cli/src/lib.rs
+++ b/crates/uv-cli/src/lib.rs
@@ -625,6 +625,14 @@ pub enum PipCommand {
     )]
     Compile(PipCompileArgs),
     /// Sync an environment with a `requirements.txt` file.
+    ///
+    /// When syncing an environment, any packages not listed in the `requirements.txt` file will
+    /// be removed. To retain extraneous packages, use `uv pip install` instead.
+    ///
+    /// The `requirements.txt` file is presumed to be the output of a `pip compile` or `uv export`
+    /// operation, in which it will include all transitive dependencies. If transitive dependencies
+    /// are not present in the file, they will not be installed. Use `--strict` to warn if any
+    /// transitive dependencies are missing.
     #[command(
         after_help = "Use `uv help pip sync` for more details.",
         after_long_help = ""
diff --git a/docs/reference/cli.md b/docs/reference/cli.md
index 95f0ebde9..293a41e6c 100644
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@@ -6111,7 +6111,11 @@ uv pip compile [OPTIONS] <SRC_FILE|--group <GROUP>>
 
 ### uv pip sync
 
-Sync an environment with a `requirements.txt` file
+Sync an environment with a `requirements.txt` file.
+
+When syncing an environment, any packages not listed in the `requirements.txt` file will be removed. To retain extraneous packages, use `uv pip install` instead.
+
+The `requirements.txt` file is presumed to be the output of a `pip compile` or `uv export` operation, in which it will include all transitive dependencies. If transitive dependencies are not present in the file, they will not be installed. Use `--strict` to warn if any transitive dependencies are missing.
 
 <h3 class="cli-reference">Usage</h3>