Gemini CLI Built-in Tools

Gemini CLI Built-in Tools

Reference for Gemini's built-in tools and their capabilities.

Unique Tools (Not in Claude Code)

These tools are available only through Gemini CLI:

google_web_search

Performs web search using Google Search API.

Capabilities:

• Real-time internet search
• Current information (news, releases, docs)
• Grounded responses with sources

Usage:

gemini "What are the latest React 19 features? Use Google Search." -o text

Best For:

• Current events and news
• Latest library versions
• Recent documentation updates
• Community opinions and benchmarks

Example Queries:

• "What are the security vulnerabilities in lodash 4.x? Use Google Search."
• "What's new in TypeScript 5.4? Use Google Search."
• "Best practices for Next.js 14 app router in November 2025."

codebase_investigator

Specialized agent for deep codebase analysis.

Note: This is an experimental agent feature introduced in late 2025. It may require opt-in via Preview Features in /settings. Behavior and availability may change between versions.

Capabilities:

• Architectural mapping
• Dependency analysis
• Cross-file relationship detection
• System-wide pattern identification
• Multi-file change proposals (approve/reject step by step)

Usage:

gemini "Use the codebase_investigator tool to analyze this project" -o text

Output Includes:

• Overall architecture description
• Key file purposes
• Component relationships
• Dependency chains
• Potential issues/inconsistencies

Best For:

• Onboarding to new codebases
• Understanding legacy systems
• Finding hidden dependencies
• Architecture documentation

Example:

gemini "Use codebase_investigator to map the authentication flow in this project" -o text

save_memory

Saves information to persistent long-term memory.

Capabilities:

• Cross-session persistence
• Key-value storage
• Recall in future sessions

Usage:

gemini "Remember that this project uses Zustand for state management. Save this to memory." -o text

Best For:

• Project conventions
• User preferences
• Recurring context
• Custom instructions

Standard Tools

These tools are similar to Claude Code's capabilities:

list_directory

Lists files and subdirectories in a path.

Parameters:

• path: Directory to list
• ignore: Glob patterns to exclude

Example Output:

src/
  components/
  utils/
  index.js
package.json
README.md

read_file

Reads file content with truncation for large files.

Supported Formats:

• Text files (all types)
• Images (PNG, JPG, GIF, WEBP, SVG, BMP)
• PDF documents

Parameters:

• path: File path
• offset: Starting line (for large files)
• limit: Number of lines

Large File Handling: If file exceeds limit, output indicates truncation and provides instructions for reading more with offset/limit.

search_file_content

Fast content search powered by ripgrep.

Advantages over grep:

• Optimized performance
• Automatic output limiting (max 20k matches)
• Better pattern matching

Parameters:

• pattern: Regex pattern
• path: Search root
• Various ripgrep flags

glob

Pattern-based file finding.

Returns:

• Absolute paths
• Sorted by modification time (newest first)

Example Patterns:

• src/**/*.ts - All TypeScript files in src
• **/*.test.js - All test files
• **/README.md - All READMEs

web_fetch

Fetches content from URLs.

Capabilities:

• HTTP/HTTPS URLs
• Local addresses (localhost)
• Up to 20 URLs per request

Usage:

gemini "Fetch and summarize https://example.com/docs" -o text

write_todos

Internal task tracking.

Capabilities:

• Track subtasks for complex requests
• Organize multi-step work
• Prevent missed steps

Automatic Usage: Gemini uses this internally for complex tasks.

Tool Invocation

Automatic Tool Selection

Gemini automatically selects appropriate tools based on the prompt:

Explicit Tool Requests

You can explicitly request tools:

gemini "Use the codebase_investigator tool to..." -o text
gemini "Search the web for..." -o text
gemini "Use glob to find all..." -o text

Tool Statistics in JSON Output

When using -o json, tool usage is reported:

{
  "stats": {
    "tools": {
      "totalCalls": 3,
      "totalSuccess": 3,
      "totalFail": 0,
      "totalDurationMs": 5000,
      "totalDecisions": {
        "accept": 0,
        "reject": 0,
        "modify": 0,
        "auto_accept": 3
      },
      "byName": {
        "google_web_search": {
          "count": 1,
          "success": 1,
          "fail": 0,
          "durationMs": 3000,
          "decisions": {
            "auto_accept": 1
          }
        },
        "read_file": {
          "count": 2,
          "success": 2,
          "fail": 0,
          "durationMs": 2000,
          "decisions": {
            "auto_accept": 2
          }
        }
      }
    }
  }
}

Comparison with Claude Code Tools

Bold = Gemini's unique advantage

Tool Restrictions

Using allowed-tools

In settings or command line, restrict available tools:

gemini --allowed-tools "read_file,glob" "Find config files" -o text

In Settings

{
  "security": {
    "allowedTools": ["read_file", "list_directory", "glob"]
  }
}

Best Practices

When to Use Specific Tools

google_web_search:

• Need current/recent information
• Checking latest versions
• Finding documentation updates
• Community solutions to problems

codebase_investigator:

• New to a codebase
• Understanding complex systems
• Finding hidden dependencies
• Creating documentation

save_memory:

• Recurring project context
• User preferences
• Custom conventions

Tool Combination Patterns

Research → Implement:

gemini "Use Google Search to find best practices for [topic], then implement them" --approval-mode yolo -o text

Analyze → Report:

gemini "Use codebase_investigator to analyze the project, then write a summary report" --approval-mode yolo -o text

Search → Read → Modify:

gemini "Find all files using deprecated API, read them, and suggest updates" -o text