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# Gemini CLI Extension - MCP Toolbox
> [!NOTE]
> This extension is currently in beta (pre-v1.0), and may see breaking changes until the first stable release (v1.0).
Develop and query your custom tools using the power of natural language, directly
from your command line through [MCP
Toolbox](https://github.com/googleapis/mcp-toolbox). Go from an idea to a
running, invocable tool in minutes, without ever leaving your terminal.
Learn more about [Gemini CLI Extensions](https://github.com/google-gemini/gemini-cli/blob/main/docs/extensions/index.md).
> [!IMPORTANT]
> **We Want Your Feedback!**
> Please share your thoughts with us by filling out our feedback [form][form].
> Your input is invaluable and helps us improve the project for everyone.
[form]: https://docs.google.com/forms/d/e/1FAIpQLSfEGmLR46iipyNTgwTmIDJqzkAwDPXxbocpXpUbHXydiN1RTw/viewform?usp=pp_url&entry.157487=mcp-toolbox
## Why Use the MCP Toolbox Extension?
* **Reliable Custom Servers:** Quickly create a **custom MCP server** with tools designed to reliably return accurate results. This saves significant development time and cost by ensuring your agent gets precise data without extensive guidance or fine-tuning.
* **Enterprise Data Awareness:** Instantly upgrade your developer environment by providing your agents with **enterprise-grade data awareness**. Connect your AI systems directly to your data sources for smarter, more relevant operations.
* **Accelerated Agent Development:** Fast-track your AI project by easily testing and validating tool usage with a **pre-built agent environment**.
## Prerequisites
Before you begin, ensure you have the following:
* [Gemini CLI](https://github.com/google-gemini/gemini-cli) installed with version **+v0.6.0**.
* Setup Gemini CLI [Authentication](https://github.com/google-gemini/gemini-cli/tree/main?tab=readme-ov-file#-authentication-options).
* Any required APIs and permissions for connecting to your database.
## Getting Started
### Installation
```bash
gemini extensions install https://github.com/gemini-cli-extensions/mcp-toolbox
```
### Configuration
* Add your [`tools.yaml` configuration file](https://mcp-toolbox.dev/documentation/configuration/) to the directory you
are running Gemini CLI.
Ensure [Application Default Credentials](https://cloud.google.com/docs/authentication/gcloud) are available in your environment if connecting to Google Cloud services.
### Start Gemini CLI
To start the Gemini CLI, use the following command:
```bash
gemini
```
## Usage
Interact with your custom tools using natural language.
## Additional Extensions
Find additional extensions to support your entire software development lifecycle at [github.com/gemini-cli-extensions](https://github.com/gemini-cli-extensions), including a generic [PostgreSQL extension](https://github.com/gemini-cli-extensions/postgres).
## Troubleshooting
Use `gemini --debug` to enable debugging.
Common issues:
* "failed to find default credentials: google: could not find default credentials.": Ensure [Application Default Credentials](https://cloud.google.com/docs/authentication/gcloud) are available in your environment. See [Set up Application Default Credentials](https://cloud.google.com/docs/authentication/external/set-up-adc) for more information.
* "✖ Error during discovery for server: MCP error -32000: Connection closed": The database connection has not been established. Ensure your configuration is set via environment variables.
* "✖ MCP ERROR: Error: spawn /Users/USER/.gemini/extensions/mcp-toolbox/toolbox ENOENT": The Toolbox binary did not download correctly. Ensure you are using Gemini CLI v0.6.0+.
* "cannot execute binary file": The Toolbox binary did not download correctly. Ensure the correct binary for your OS/Architecture has been downloaded. See [Installing the server](https://mcp-toolbox.dev/documentation/introduction/#install-toolbox) for more information.
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