# Tools

An agent can use tools autonomously or with supervision.

## Define tools

A tool is defined as a `ToolSpec` object with these fields:

- `name` — unique identifier for the tool
- `description` — what the tool does
- `arguments` — schema of expected arguments
- `type` — tool type (e.g., `"action"`, `"task"`)
- `parallelCalls` — whether multiple instances can run in parallel
- `execute` — async function that runs the tool logic
- `canRun` — optional authorization callback

Create a tool execution function:

```typescript
async function get_current_weather(args: { location?: string }) {
    const location = args?.location ?? "unknown";
    console.log("Running get_current_weather for", location);
    return { temp: 20.5, weather: "rain" };
}
```

Create a tool definition matching the `ToolSpec` interface:

```typescript
const weatherTool = {
    name: "get_current_weather",
    description: "Get the current weather for a location",
    arguments: {
        location: {
            description: "The city and state, e.g. San Francisco, CA",
            type: "string",
            required: true,
        },
    },
    type: "action",
    parallelCalls: false,
    execute: get_current_weather,
};
```

## Configure an agent with tools

Initialize an agent connected to an OpenRouter backend:

```typescript
import { Lm, Agent } from "@agent-smith/agent";

const lm = new Lm({
    name: "openrouter",
    serverUrl: "https://openrouter.ai/api/v1",
    apiKey: process.env.OPENROUTER_API_KEY,
});

const agent = new Agent({
    name: "weather-agent",
    lm,
    onToken: (t) => process.stdout.write(t),
});
```

Run the agent with tools:

```typescript
const prompt = `I am landing in Barcelona soon: I plan to reach my hotel 
and then go for outdoor sport. How are the conditions in the city?`;

const result = await agent.run(prompt, {
    params: {
        model: "qwen/qwen3-30b-a3b:free",
        temperature: 0.4,
        top_k: 40,
        top_p: 0.95,
        min_p: 0,
        max_tokens: 16384,
    },
    debug: true,
    tools: [weatherTool],
});
```

The agent will autonomously call `get_current_weather` when it determines the tool is useful.

<a href="javascript:openLink('/libraries/agent/templates')">Next: templates</a>