Docs: Add /model documentation (#12654)

docs/cli/commands.md

@@ -121,6 +121,9 @@ Slash commands provide meta-level control over the CLI itself.
       - **Description:** Restarts all MCP servers and re-discovers their
         available tools.
 
+- [**`/model`**](./model.md)
+  - **Description:** Opens a dialog to choose your Gemini model.
+
 - **`/memory`**
   - **Description:** Manage the AI's instructional context (hierarchical memory
     loaded from `GEMINI.md` files).

docs/cli/model.md

@@ -0,0 +1,44 @@
+# Gemini CLI Model Selection (`/model` Command)
+
+Select your Gemini CLI model. The `/model` command opens a dialog where you can
+configure the model used by Gemini CLI, giving you more control over your
+results.
+
+## How to use the `/model` command
+
+Use the following command in Gemini CLI:
+
+```
+/model
+```
+
+Running this command will open a dialog with your model options:
+
+- **Auto (recommended):** Let the system choose the best model for your task.
+  Typically, this is the best option.
+- **Pro:** For complex tasks that require deep reasoning and creativity. The Pro
+  model may take longer to return a response.
+- **Flash:** For tasks that need a balance of speed and reasoning. The Flash
+  model will usually return a faster response than Pro.
+- **Flash-Lite:** For simple tasks that need to be done quickly. The Flash-Lite
+  model is typically the fastest.
+
+Changes to these settings will be applied to all subsequent interactions with
+Gemini CLI.
+
+## Best practices for model selection
+
+- **Default to Auto (recommended).** For most users, the _Auto (recommended)_
+  model provides a balance between speed and performance, automatically
+  selecting the correct model based on the complexity of the task. Example:
+  Developing a web application could include a mix of complex tasks (building
+  architecture and scaffolding the project) and simple tasks (generating CSS).
+
+- **Switch to Pro if you aren't getting the results you want.** If you think you
+  need your model to be a little "smarter," use Pro. Pro will provide you with
+  the highest levels of reasoning and creativity. Example: A complex or
+  multi-stage debugging task.
+
+- **Switch to Flash or Flash-Lite if you need faster results.** If you need a
+  simple response quickly, Flash or Flash-Lite is the best option. Example:
+  Converting a JSON object to a YAML string.

docs/sidebar.json

@@ -72,6 +72,10 @@
         "label": "Keyboard Shortcuts",
         "slug": "docs/cli/keyboard-shortcuts"
       },
+      {
+        "label": "Model Selection",
+        "slug": "docs/cli/model"
+      },
       {
         "label": "Sandbox",
         "slug": "docs/cli/sandbox"