Starting with version 1.5.0, developers can override built-in commands or add commands without forking the CLI.
An extension is a directory in a Git repository containing an agents-cli-extension.yaml file. Extensions can be installed at project scope, where they are committed with a project, or globally for a user. When both scopes define the same command, the project-scoped extension takes precedence.
Version 1.8.0 includes a first-party LangChain extension. Google says it replaces framework-coupled commands with LangChain equivalents while retaining the rest of the CLI workflow for scaffolding, running, deploying, and evaluating agents. The company also demonstrates a custom deploy wrapper that runs a software bill of materials scan.
The source describes the extension interface and examples, but does not establish adoption, compatibility with every agent framework, or the effectiveness of organizational policy checks implemented through extensions.