ADK Tools

Guide for extending agent capabilities with tools. Covers custom functions, API integrations, and external frameworks.

When to Use

• Adding custom Python functions as tools
• Integrating external APIs
• Connecting MCP servers
• Using built-in ADK tools
• Handling long-running operations
• Computer use capabilities
• LangChain/LlamaIndex tool integration

When NOT to Use

• Initial project setup → Use @adk-core instead
• Creating agents → Use @adk-core instead
• Multi-agent coordination → Use @adk-orchestration instead
• Security policies → Use @adk-production instead

Key Concepts

FunctionTool wraps Python functions into agent-callable tools. Docstrings become tool descriptions, type hints define parameters.

Built-in Tools like google_search and code_execution are pre-configured and ready to use via tool name.

MCP Integration connects Model Context Protocol servers as tool sources. Configure in adk.yaml or via .mcp.json.

OpenAPI Tools auto-generate from API specifications. ADK creates typed tools from your OpenAPI schemas.

Long-Running Tools use async patterns or callbacks for operations that exceed typical timeouts.

Computer Use Tools provide screen, keyboard, and mouse control for desktop automation tasks.

Third-Party Frameworks like LangChain and LlamaIndex expose their tool ecosystems to ADK agents.

Implementation Pattern

from adk.tools import FunctionTool
from adk import LlmAgent

def calculate_area(length: float, width: float) -> float:
    """Calculate rectangle area."""
    return length * width

area_tool = FunctionTool(calculate_area)
agent = LlmAgent(tools=[area_tool])

References

Detailed guides with code examples:

• references/tools-function.md - Custom Python tools
• references/tools-builtin.md - Pre-configured tools
• references/tools-mcp.md - MCP server integration
• references/tools-openapi.md - OpenAPI schemas
• references/tools-async.md - Long-running operations
• references/tools-computer-use.md - Desktop automation
• references/tools-third-party.md - LangChain/LlamaIndex