Tool Use untuk AI Agent

Tools membuat agent bisa berinteraksi dengan dunia nyata: mencari web, mengirim email, mengupdate database, menjalankan code.

Function Calling (OpenAI)

const tools = [
  {
    type: "function",
    function: {
      name: "search_web",
      description: "Cari informasi di web",
      parameters: {
        type: "object",
        properties: {
          query: { type: "string", description: "Search query" },
          num_results: { type: "number", description: "Jumlah hasil (default 5)" },
        },
        required: ["query"],
      },
    },
  },
  {
    type: "function",
    function: {
      name: "read_file",
      description: "Baca isi file",
      parameters: {
        type: "object",
        properties: {
          path: { type: "string", description: "Path ke file" },
        },
        required: ["path"],
      },
    },
  },
];

const response = await openai.chat.completions.create({
  model: "gpt-4o",
  messages,
  tools,
  tool_choice: "auto",
});

Tool Execution

async function handleToolCalls(response: any) {
  const toolCalls = response.choices[0].message.tool_calls;
  if (!toolCalls) return null;

  const results = [];

  for (const call of toolCalls) {
    const { name, arguments: args } = call.function;
    const parsed = JSON.parse(args);

    let result;
    switch (name) {
      case "search_web":
        result = await webSearch(parsed.query, parsed.num_results);
        break;
      case "read_file":
        result = await readFile(parsed.path);
        break;
      default:
        result = { error: "Unknown tool: " + name };
    }

    results.push({
      tool_call_id: call.id,
      role: "tool",
      content: JSON.stringify(result),
    });
  }

  return results;
}

Tool Registry Pattern

class ToolRegistry {
  private tools = new Map<string, Tool>();

  register(tool: Tool) {
    this.tools.set(tool.name, tool);
  }

  async execute(name: string, params: any): Promise<any> {
    const tool = this.tools.get(name);
    if (!tool) throw new Error("Tool not found: " + name);

    // Safety check
    if (!tool.isAllowed(params)) {
      throw new Error("Tool call not allowed: " + name);
    }

    return await tool.execute(params);
  }

  getDefinitions() {
    return Array.from(this.tools.values()).map((t) => t.toFunctionDef());
  }
}

// Register tools
const registry = new ToolRegistry();
registry.register(new WebSearchTool());
registry.register(new ReadFileTool());
registry.register(new SendEmailTool({ allowedRecipients: ["@company.com"] }));

Safety Guardrails

class SafeTool implements Tool {
  constructor(
    private inner: Tool,
    private rules: SafetyRules
  ) {}

  async execute(params: any): Promise<any> {
    // 1. Rate limiting
    await this.checkRateLimit();

    // 2. Parameter validation
    this.validateParams(params);

    // 3. Dry run check
    if (this.rules.dryRun) {
      return { dryRun: true, wouldExecute: this.inner.name, params };
    }

    // 4. Human approval (untuk destructive actions)
    if (this.rules.requiresApproval) {
      const approved = await requestHumanApproval(this.inner.name, params);
      if (!approved) return { rejected: "User rejected action" };
    }

    // 5. Execute
    const result = await this.inner.execute(params);

    // 6. Log
    await this.log(this.inner.name, params, result);

    return result;
  }
}

Common Tools

| Tool | Function | Safety Level | |------|----------|-------------| | web_search | Cari di internet | Low risk | | read_file | Baca file | Low risk | | write_file | Tulis file | Medium risk | | execute_code | Jalankan kode | High risk | | send_email | Kirim email | High risk | | database_write | Update database | Critical |

Vercel AI SDK Tool Use

import { tool } from "ai";
import { z } from "zod";

const weatherTool = tool({
  description: "Get weather for a location",
  parameters: z.object({
    location: z.string().describe("City name"),
  }),
  execute: async ({ location }) => {
    const response = await fetch("https://api.weather.com/" + location);
    return response.json();
  },
});

const result = await generateText({
  model: openai("gpt-4o"),
  messages,
  tools: { weather: weatherTool },
  maxSteps: 5, // Allow multi-step tool use
});

Latihan

Buat 3 tools (search, read, summarize) dan implementasikan agent yang bisa menggunakannya untuk meriset topik.