adk-tool

Tool system for Rust Agent Development Kit (ADK-Rust) agents (FunctionTool, MCP, Google Search).

Overview

adk-tool provides the tool infrastructure for the Rust Agent Development Kit (ADK-Rust):

• FunctionTool - Create tools from async Rust functions
• AgentTool - Use agents as callable tools for composition
• GoogleSearchTool - Web search via Gemini's grounding
• McpToolset - Model Context Protocol integration
• BasicToolset - Group multiple tools together
• ExitLoopTool - Control flow for loop agents
• LoadArtifactsTool - Inject binary artifacts into context

Installation

[dependencies]
adk-tool = "0.2.0"

Or use the meta-crate:

[dependencies]
adk-rust = { version = "0.2.1", features = ["tools"] }

Quick Start

Function Tool

use adk_tool::FunctionTool;
use adk_core::{ToolContext, Result};
use serde_json::{json, Value};
use std::sync::Arc;

async fn get_weather(_ctx: Arc<dyn ToolContext>, args: Value) -> Result<Value> {
    let city = args["city"].as_str().unwrap_or("Unknown");
    Ok(json!({
        "city": city,
        "temperature": 72,
        "condition": "sunny"
    }))
}

let tool = FunctionTool::new(
    "get_weather",
    "Get current weather for a city",
    get_weather,
);

With Parameter Schema (Recommended)

Always add a schema so the LLM knows what parameters to pass:

use schemars::JsonSchema;
use serde::{Deserialize, Serialize};

#[derive(JsonSchema, Serialize, Deserialize)]
struct WeatherParams {
    /// The city to get weather for
    city: String,
}

let tool = FunctionTool::new("get_weather", "Get weather", get_weather)
    .with_parameters_schema::<WeatherParams>();

MCP Tools

use adk_tool::McpToolset;
use rmcp::{ServiceExt, transport::TokioChildProcess};

let client = ().serve(TokioChildProcess::new(
    Command::new("npx")
        .arg("-y")
        .arg("@modelcontextprotocol/server-filesystem")
        .arg("/path/to/files")
)?).await?;

let toolset = McpToolset::new(client)
    .with_filter(|name| matches!(name, "read_file" | "write_file"));

Google Search

use adk_tool::GoogleSearchTool;

let search = GoogleSearchTool::new();
// Add to agent - enables grounded web search

Features

• Type-safe parameter schemas with schemars
• Long-running tool support with progress tracking
• MCP protocol for external tool integration
• Tool filtering and composition

Related Crates

• adk-rust - Meta-crate with all components
• adk-core - Core Tool trait
• adk-agent - Agents that use tools

License

Apache-2.0

Part of ADK-Rust

This crate is part of the ADK-Rust framework for building AI agents in Rust.