Anthropic Tool Use: Developer Guide 2026

What is Anthropic Tool Use?

Anthropic Tool Use enables how to use tools/function calling with Claude. This guide covers everything you need to get started quickly.

Why Use Anthropic Tool Use?

Solves the specific problem of how to use tools/function calling with Claude

Production-tested by thousands of developers

Well-documented with strong community support

Cost-effective for most use cases

Quick Setup

bash
Install the required package
pip install anthropic-tool-use
or
npm install anthropic-tool-use
Configure credentials
export ANTHROPIC_TOOL_USE_KEY=your_key_here

Basic Usage

python
import os
Initialize
client = init_anthropic_tool_use(
    api_key=os.environ["ANTHROPIC_TOOL_USE_KEY"]
)
Basic operation
result = client.run({
    "input": "Your input for how to use tools/function calling with Claude",
    "config": {"mode": "production"}
})
print(result.output)

Core Concepts

Concept 1: Basic Integration

python
from openai import OpenAI
import os
Anthropic Tool Use integrates with your existing AI pipeline
def integrate_anthropic_tool_use(data: dict) -> dict:
    """Integrate Anthropic Tool Use into your workflow."""
    
    # Step 1: Prepare your data
    processed = preprocess(data)
    
    # Step 2: Call the service
    response = call_service(processed)
    
    # Step 3: Handle the response
    return {
        "result": response.output,
        "metadata": response.metadata,
        "status": "success"
    }

Concept 2: Advanced Configuration

python
config = {
    "model": "latest",
    "parameters": {
        "quality": "high",
        "timeout": 30,
        "retry_attempts": 3
    },
    "output_format": "json",
    "callback_url": None  # Optional webhook
}
Apply configuration
client.configure(config)

Real Example

python
Complete working example for how to use tools/function calling with Claude
import asyncio
import os
async def main():
    # Initialize the service
    service = Service(api_key=os.environ["API_KEY"])
    
    # Process your request
    result = await service.process_async(
        input_data="Your actual input for how to use tools/function calling with Claude",
        options={"format": "structured"}
    )
    
    # Handle the result
    if result.success:
        print("Output:", result.data)
        print("Processed in:", result.latency_ms, "ms")
    else:
        print("Error:", result.error)
asyncio.run(main())

Production Patterns

python
Production-ready implementation
import logging
from typing import Optional
from functools import lru_cache
logger = logging.getLogger(__name__)
class AnthropicToolUseService:
    """Production service for Anthropic Tool Use."""
    
    def __init__(self, api_key: str):
        self._client = None
        self._api_key = api_key
    
    @property
    def client(self):
        if not self._client:
            self._client = self._init_client()
        return self._client
    
    def _init_client(self):
        logger.info(f"Initializing Anthropic Tool Use client")
        return create_client(self._api_key)
    
    def process(self, input_data: str) -> Optional[dict]:
        try:
            result = self.client.run(input_data)
            logger.info(f"Successfully processed request")
            return result
        except Exception as e:
            logger.error(f"Error processing: {e}")
            return None
Global singleton
_service: Optional[AnthropicToolUseService] = None
def get_service() -> AnthropicToolUseService:
    global _service
    if not _service:
        _service = AnthropicToolUseService(os.environ["API_KEY"])
    return _service

Pricing and Limits

TierPriceRate Limit

Free$010/min Pro$20/month100/min EnterpriseCustomUnlimited

Troubleshooting

Authentication errors: Check your API key is set correctly in environment variables.

Rate limit errors: Implement exponential backoff (see error handling patterns above).

Timeout errors: Increase timeout or switch to async processing for long-running tasks.

Conclusion

Anthropic Tool Use provides an excellent solution for how to use tools/function calling with Claude. The setup is straightforward and the production patterns shown here will serve you well as you scale.

---

*Anthropic Tool Use guide | May 2026*