Added usage details to /tools command. (#6849)

Co-authored-by: Bryan Morgan <bryanmorgan@google.com>

docs/cli/commands.md

@@ -110,6 +110,7 @@ Slash commands provide meta-level control over the CLI itself.
 
 - [**`/tools`**](../tools/index.md)
   - **Description:** Display a list of tools that are currently available within Gemini CLI.
+  - **Usage:** `/tools [desc]`
   - **Sub-commands:**
     - **`desc`** or **`descriptions`**:
       - **Description:** Show detailed descriptions of each tool, including each tool's name with its full description as provided to the model.