diff --git a/crates/uv-cli/src/lib.rs b/crates/uv-cli/src/lib.rs
index ede53be980c2e..4bcc5a3eaccf1 100644
--- a/crates/uv-cli/src/lib.rs
+++ b/crates/uv-cli/src/lib.rs
@@ -548,22 +548,24 @@ pub enum ProjectCommand {
     ///
     /// Dependencies are added to the project's `pyproject.toml` file.
     ///
-    /// If no constraint or URL is provided for a dependency, a lower bound is
-    /// added equal to the latest compatible version of the package, e.g.,
-    /// `>=1.2.3`, unless `--frozen` is provided, in which case no resolution is
-    /// performed.
+    /// If a given depedency exists already, it will be updated to the new version specifier unless
+    /// it includes markers that differ from the existing specifier in which case another entry for
+    /// the depenedency will be added.
     ///
-    /// The lockfile and project environment will be updated to reflect the
-    /// added dependencies. To skip updating the lockfile, use `--frozen`. To
-    /// skip updating the environment, use `--no-sync`.
+    /// If no constraint or URL is provided for a dependency, a lower bound is added equal to the
+    /// latest compatible version of the package, e.g., `>=1.2.3`, unless `--frozen` is provided, in
+    /// which case no resolution is performed.
     ///
-    /// If any of the requested dependencies cannot be found, uv will exit with
-    /// an error, unless the `--frozen` flag is provided, in which case uv will
-    /// add the dependencies verbatim without checking that they exist or are
-    /// compatible with the project.
+    /// The lockfile and project environment will be updated to reflect the added dependencies. To
+    /// skip updating the lockfile, use `--frozen`. To skip updating the environment, use
+    /// `--no-sync`.
     ///
-    /// uv will search for a project in the current directory or any parent
-    /// directory. If a project cannot be found, uv will exit with an error.
+    /// If any of the requested dependencies cannot be found, uv will exit with an error, unless the
+    /// `--frozen` flag is provided, in which case uv will add the dependencies verbatim without
+    /// checking that they exist or are compatible with the project.
+    ///
+    /// uv will search for a project in the current directory or any parent directory. If a project
+    /// cannot be found, uv will exit with an error.
     #[command(
         after_help = "Use `uv help add` for more details.",
         after_long_help = ""
@@ -573,6 +575,9 @@ pub enum ProjectCommand {
     ///
     /// Dependencies are removed from the project's `pyproject.toml` file.
     ///
+    /// If multiple entries exist for a given dependency, i.e., each with different markers, all of
+    /// the entries will be removed.
+    ///
     /// The lockfile and project environment will be updated to reflect the
     /// removed dependencies. To skip updating the lockfile, use `--frozen`. To
     /// skip updating the environment, use `--no-sync`.
diff --git a/docs/reference/cli.md b/docs/reference/cli.md
index 90cf40aae2fb6..7c42d3af16f83 100644
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@@ -455,6 +455,8 @@ Add dependencies to the project (experimental).
 
 Dependencies are added to the project's `pyproject.toml` file.
 
+If a given depedency exists already, it will be updated to the new version specifier unless it includes markers that differ from the existing specifier in which case another entry for the depenedency will be added.
+
 If no constraint or URL is provided for a dependency, a lower bound is added equal to the latest compatible version of the package, e.g., `>=1.2.3`, unless `--frozen` is provided, in which case no resolution is performed.
 
 The lockfile and project environment will be updated to reflect the added dependencies. To skip updating the lockfile, use `--frozen`. To skip updating the environment, use `--no-sync`.
@@ -735,6 +737,8 @@ Remove dependencies from the project (experimental).
 
 Dependencies are removed from the project's `pyproject.toml` file.
 
+If multiple entries exist for a given dependency, i.e., each with different markers, all of the entries will be removed.
+
 The lockfile and project environment will be updated to reflect the removed dependencies. To skip updating the lockfile, use `--frozen`. To skip updating the environment, use `--no-sync`.
 
 If any of the requested dependencies are not present in the project, uv will exit with an error.