Develop and query your custom tools using the power of natural language, directly from your command line through MCP Toolbox. Go from an idea to a running, invocable tool in minutes, without ever leaving your terminal.

Learn more about Gemini CLI Extensions.

• 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.

Before you begin, ensure you have the following:

• Gemini CLI installed with version +v0.6.0.
• Setup Gemini CLI Authentication.
• Any required APIs and permissions for connecting to your database.

gemini extensions install https://github.com/gemini-cli-extensions/mcp-toolbox

• Add your tools.yaml configuration file to the directory you are running Gemini CLI.

Ensure Application Default Credentials are available in your environment if connecting to Google Cloud services.

To start the Gemini CLI, use the following command:

gemini

Interact with your custom tools using natural language.

Find additional extensions to support your entire software development lifecycle at github.com/gemini-cli-extensions, including a generic PostgreSQL extension.

Use gemini --debug to enable debugging.

Common issues:

• "failed to find default credentials: google: could not find default credentials.": Ensure Application Default Credentials are available in your environment. See Set up Application Default Credentials 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 for more information.