> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# tool • AI Agent SDK
> tool: Decorator to convert a function into a tool.
# tool
Function
> This function is defined in the [**decorator**](../modules/decorator) module.
Decorator to convert a function into a tool.
Can be used with or without arguments:
@tool
def my\_func(x: str) -> str:
'''Does something.'''
return x
@tool(name="custom\_name", description="Custom description")
def my\_func(x: str) -> str:
return x
@tool(availability=lambda: (bool(os.getenv("API\_KEY")), "API\_KEY missing"))
def my\_func(x: str) -> str:
return x
@tool(retry\_policy=RetryPolicy(max\_attempts=5))
def my\_func(x: str) -> str:
return x
@tool(approval=True)
def delete\_account(user\_id: str) -> str:
return "deleted"
@tool(approval="critical")
def deploy(env: str) -> str:
return "deployed"
```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#8B0000', 'primaryTextColor': '#fff', 'primaryBorderColor': '#710101', 'lineColor': '#189AB4', 'secondaryColor': '#189AB4', 'tertiaryColor': '#fff' }}}%%
graph LR
agent["Agent"] -- "uses" --> tool["Tool: tool"]
tool -- "returns" --> result["Result"]
style tool fill:#189AB4,color:#fff
style agent fill:#8B0000,color:#fff
style result fill:#8B0000,color:#fff
```
## Signature
```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
def tool(func: Optional[Callable]) -> Union[FunctionTool, Callable[[Callable], FunctionTool]]
```
## Parameters
The function to wrap (when used without parentheses)
### Returns
FunctionTool instance that wraps the function
## Uses
* `FunctionTool`
* `add_approval_requirement`
* `RuntimeError`
* `tool_instance.validate`
* `tool_instance.validate_schema_roundtrip`
* `logging.warning`
* `logging.debug`
* `get_registry`
* `registry.register`
* `decorator`
## Source
`praisonaiagents/tools/decorator.py` at line 232
***
## Related Documentation