Gemini CLI

To authenticate, use one of 3 options:

1. Login with Google (uses Gemini Code Assist licenses)
2. Gemini API key
3. Vertex AI

For Gemini API key, simply set the GEMINI_API_KEY environment variable.

To use Gemini models via Vertex AI, set these environment variables.

export GOOGLE_CLOUD_PROJECT=<PROJECT_ID>
export GOOGLE_CLOUD_LOCATION=<LOCATION>

Add project-specific context in a local GEMINI.md file.

Add general context in ~/.gemini/GEMINI.md

Example: Context7

Edit the file ~/.gemini/settings.json to add:

"mcpServers": {
  "context7": {
    "httpUrl": "https://mcp.context7.com/mcp",
    
  }
}

If the file is empty (or doesn't exist), set its contents to:

{
  "mcpServers": {
    "context7": {
      "httpUrl": "https://mcp.context7.com/mcp",
      
    }
  }
}

Example (changelog.toml):

This example shows how to create a robust command by defining a role for the model, explaining where to find the user's input, and specifying the expected format and behavior.

In: /.gemini/commands/changelog.toml

description = "Adds a new entry to the project's CHANGELOG.md file."
prompt = """
# Task: Update Changelog

You are an expert maintainer of this software project. A user has invoked a command to add a new entry to the changelog.

**The user's raw command is appended below your instructions.**

Your task is to parse the `<version>`, `<change_type>`, and `<message>` from their input and use the `write_file` tool to correctly update the `CHANGELOG.md` file.

## Expected Format
The command follows this format: `/changelog <version> <type> <message>`
- `<type>` must be one of: "added", "changed", "fixed", "removed".

## Behavior
1. Read the `CHANGELOG.md` file.
2. Find the section for the specified `<version>`.
3. Add the `<message>` under the correct `<type>` heading.
4. If the version or type section doesn't exist, create it.
5. Adhere strictly to the "Keep a Changelog" format.
"""

Now, when you run /changelog 1.2.0 added "New feature", the final text sent to the model will be the original prompt followed by two newlines and the command you typed.

For example, in the middle of a session:

/memory add Always create RESTful API endpoints when adding new API routes

The Gemini CLI includes a Checkpointing feature that automatically saves a snapshot of your project's state before any file modifications are made by AI-powered tools

When you approve a tool that modifies the file system (like write_file or replace), the CLI automatically creates a "checkpoint." This checkpoint includes:

1. A Git Snapshot: A commit is made in a special, shadow Git repository located in your home directory (~/.gemini/history/<project_hash>). This snapshot captures the complete state of your project files at that moment. It does not interfere with your own project's Git repository.
2. Conversation History: The entire conversation you've had with the agent up to that point is saved.
3. The Tool Call: The specific tool call that was about to be executed is also stored.

Gemini CLI can also work in headless mode. Great for automation, background tasks, or quick questions:

gemini -p "Explain the architecture in this codebase"

While chat histories are kept automatically, you can save conversations with a given name for easier retrieval (and/or longer retention):

/chat save mytag1
/chat list
/chat resume mytag1
/chat delete mytag1

Very useful for long debugging sessions or when you want to “park” a conversation until later.

You have gemini work with multiple directories by starting with the --include-directories option:

gemini --include-directories backend frontend

During a session, you can type the @ symbol and start typing the name of the file you want to refer to. The CLI will automatically display matching files

If you wrapped up an implementation part and want to move on to another but still keep a high-level summary of what was done, the /compress command is ideal for this.

Context compression will run automatically when the context is exhausted. But you can trigger your own compressions strategically, to prevent "context rot"

Gemini CLI can use Google Search natively. Ask it, for example, for update to date documentation and code samples:

Search Google ADK documentation and show me some code samples from there