crewAI/docs/en/learn/create-custom-tools.mdx

---
title: Create Custom Tools
description: Comprehensive guide on crafting, using, and managing custom tools within the CrewAI framework, including new functionalities and error handling.
icon: hammer
mode: "wide"
---

## Creating and Utilizing Tools in CrewAI

This guide provides detailed instructions on creating custom tools for the CrewAI framework and how to efficiently manage and utilize these tools,
incorporating the latest functionalities such as tool delegation, error handling, and dynamic tool calling. It also highlights the importance of collaboration tools,
enabling agents to perform a wide range of actions.

<Tip>
  **Want to publish your tool to the CrewAI platform?** Use the CLI to scaffold, publish, and share tools directly on the platform — see the [Platform Tools CLI](/en/guides/tools/platform-tools-cli) guide.

  **Prefer publishing to PyPI?** Check out the [Publish Custom Tools](/en/guides/tools/publish-custom-tools) guide to package and distribute your tool as a standalone Python library.
</Tip>

### Subclassing `BaseTool`

To create a personalized tool, inherit from `BaseTool` and define the necessary attributes, including the `args_schema` for input validation, and the `_run` method.

```python Code
from typing import Type
from crewai.tools import BaseTool
from pydantic import BaseModel, Field

class MyToolInput(BaseModel):
    """Input schema for MyCustomTool."""
    argument: str = Field(..., description="Description of the argument.")

class MyCustomTool(BaseTool):
    name: str = "Name of my tool"
    description: str = "What this tool does. It's vital for effective utilization."
    args_schema: Type[BaseModel] = MyToolInput

    def _run(self, argument: str) -> str:
        # Your tool's logic here
        return "Tool's result"
```

### Using the `tool` Decorator

Alternatively, you can use the tool decorator `@tool`. This approach allows you to define the tool's attributes and functionality directly within a function,
offering a concise and efficient way to create specialized tools tailored to your needs.

```python Code
from crewai.tools import tool

@tool("Tool Name")
def my_simple_tool(question: str) -> str:
    """Tool description for clarity."""
    # Tool logic here
    return "Tool output"
```

### Defining a Cache Function for the Tool

To optimize tool performance with caching, define custom caching strategies using the `cache_function` attribute.

```python Code
@tool("Tool with Caching")
def cached_tool(argument: str) -> str:
    """Tool functionality description."""
    return "Cacheable result"

def my_cache_strategy(arguments: dict, result: str) -> bool:
    # Define custom caching logic
    return True if some_condition else False

cached_tool.cache_function = my_cache_strategy
```

### Creating Async Tools

CrewAI supports async tools for non-blocking I/O operations. This is useful when your tool needs to make HTTP requests, database queries, or other I/O-bound operations.

#### Using the `@tool` Decorator with Async Functions

The simplest way to create an async tool is using the `@tool` decorator with an async function:

```python Code
import aiohttp
from crewai.tools import tool

@tool("Async Web Fetcher")
async def fetch_webpage(url: str) -> str:
    """Fetch content from a webpage asynchronously."""
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.text()
```

#### Subclassing `BaseTool` with Async Support

For more control, subclass `BaseTool` and implement both `_run` (sync) and `_arun` (async) methods:

```python Code
import requests
import aiohttp
from crewai.tools import BaseTool
from pydantic import BaseModel, Field

class WebFetcherInput(BaseModel):
    """Input schema for WebFetcher."""
    url: str = Field(..., description="The URL to fetch")

class WebFetcherTool(BaseTool):
    name: str = "Web Fetcher"
    description: str = "Fetches content from a URL"
    args_schema: type[BaseModel] = WebFetcherInput

    def _run(self, url: str) -> str:
        """Synchronous implementation."""
        return requests.get(url).text

    async def _arun(self, url: str) -> str:
        """Asynchronous implementation for non-blocking I/O."""
        async with aiohttp.ClientSession() as session:
            async with session.get(url) as response:
                return await response.text()
```

By adhering to these guidelines and incorporating new functionalities and collaboration tools into your tool creation and management processes,
you can leverage the full capabilities of the CrewAI framework, enhancing both the development experience and the efficiency of your AI agents.