Tailor Gemini CLI to your workflow with hooks

Effectivity within the age of brokers is not nearly writing code sooner; it is about constructing customized instruments that adapt to your particular setting. Whether or not it is advisable inject customized mission context, implement strict safety insurance policies, or automate testing workflows, a one-size-fits-all agent usually falls quick.

That’s why we’re introducing Gemini CLI hooks, a robust new method to management and customise the agentic loop, permitting you to tailor the habits of Gemini CLI with out ever having to the touch its supply code.

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What are hooks?

Hooks are scripts or applications that Gemini CLI executes at particular, predefined factors in its lifecycle. Consider them as “middleware” in your AI assistant. With hooks you possibly can simply add customized logic that runs synchronously throughout the agent loop, supplying you with the flexibility to:

Add context: Inject related info (like latest git commits, Jira tickets, or native documentation) earlier than the mannequin processes a request.
Validate actions: Evaluate and block probably harmful operations earlier than they’re executed. Proceed iterating till particular necessities are met, bettering mannequin efficiency.
Implement insurance policies: Implement organization-wide safety and compliance necessities robotically.
Log and optimize: Observe device utilization and dynamically alter device choice to enhance mannequin accuracy and cut back token prices.
Notifications: Get updates when Gemini CLI is idle, awaiting enter or requires a device affirmation.

By configuring hooks, you possibly can customise Gemini CLI to your particular mission. When an occasion fires, the CLI waits in your hook to finish earlier than persevering with, making certain your customized logic is at all times revered. This opens the door so that you can construct on prime of Gemini CLI in any approach you see match.

A compelling instance: Automated secret scanning

One of the sensible makes use of for hooks is making a safety security web. With a BeforeTool hook, you possibly can forestall the AI from by accident writing delicate knowledge, like API keys or passwords, into your codebase.

To see all of the accessible hook occasion varieties in Gemini CLI, reference the official documentation.

The hook script (.gemini/hooks/block-secrets.sh):

#!/usr/bin/env bash
# Learn hook enter from stdin
enter=$(cat)

# Extract content material being written utilizing jq
content material=$(echo "$enter" | jq -r '.tool_input.content material // .tool_input.new_string // ""')

# Examine for frequent secret patterns
if echo "$content material" | grep -qE 'api[_-]?key|password|secret|AKIA[0-9A-Z]{16}'; then
  # Return structured denial to the agent
  cat <

Shell

The configuration (.gemini/settings.json):

{
  "hooks": {
    "BeforeTool": [
      {
        "matcher": "write_file|replace",
        "hooks": [
          {
            "name": "secret-scanner",
            "type": "command",
            "command": "$GEMINI_PROJECT_DIR/.gemini/hooks/block-secrets.sh",
            "description": "Prevent committing secrets"
          }
        ]
      }
    ]
  }
}

JSON

Now, at any time when Gemini makes an attempt to jot down or edit a file, the hooks script validates the content material first. If a secret is detected, the operation is blocked, and the agent receives a transparent rationalization of why it was denied, permitting it to self-correct.

Greatest practices for hooks

To make sure your hooks improve your workflow with out slowing you down, we suggest following a number of key tips:

Preserve hooks quick: As a result of they run synchronously, any delay in your script will delay the agent’s response; use parallel operations and caching for costly duties.
Use particular matchers: As an alternative of operating a hook for each single device, use the matcher property (e.g., "matcher": "write_file|change") to restrict execution to related occasions.
Safety first: Hooks execute together with your consumer privileges, so at all times overview the supply of project-level hooks earlier than enabling them.

Leverage the tooling: Use the /hooks command to indicate all hooks and their standing.

Hooks in Gemini CLI extensions

The facility of hooks is not restricted to your native configuration. Gemini CLI extensions now include full help for hooks. Extension authors can bundle hooks immediately inside their extension, permitting customers to put in them with a single command and no handbook configuration. See the extensions documentation on hooks to be taught extra on the best way to add hooks to your extension.

Hooks help brings a brand new wave of what’s potential with Gemini CLI extensions. One instance being the Ralph extension, which implements the viral “Ralph loop” method. By leveraging an AfterAgent hook, the extension intercepts the agent’s completion sign and forces it right into a steady, iterative loop.

This permits Gemini CLI to persistently proceed away at tough duties whereas robotically refreshing its context between makes an attempt to stop the context rot that usually plagues lengthy periods. It transforms Gemini CLI from a reactive assistant right into a tireless, autonomous employee that does not cease till the job is finished.

One other instance of an extension with hooks is a Gemini CLI staff member’s evolution of the “Ralph loop” method which follows a extra inflexible, iterative software program growth lifecycle course of (with a little bit of character and humor). View the extension right here.