# rig-tool-macro
Rather than satisfy the rig `Tool` trait explicitly, you can annotate the tools
with the `#[tool]` attribute. This will automatically generate the `Tool`
implementation for you.
```rust
#[tool]
fn how_many_rs(s: String) -> anyhow::Result<usize> {
Ok(s.chars()
.filter(|c| *c == 'r' || *c == 'R')
.collect::<Vec<_>>()
.len())
}
```
and then call it:
```rust
#[tokio::main]
async fn main() -> anyhow::Result<()> {
let agent = providers::openai::Client::from_env()
.agent(providers::openai::GPT_4O)
.tool(HowManyRs) // <- generated by the macro
.max_tokens(1024)
let res = agent.prompt("how many Rs are in the word strawberry?").await?;
println!("{}", res);
Ok(())
}
```
You can also include descriptions for the tools
```rust
#[tool(description = "
it is important to describe ambiguous tools to LLMs
https://docs.anthropic.com/en/docs/build-with-claude/tool-use#best-practices-for-tool-definitions
this works multi-line too!
")]
fn asdf() -> Result<()> {
Ok(())
}
The current implementation supports standard types and non-nested inputs
Structs and nested stuff might come at some point, for now tools have to take
top level inputs comprised of standard types
Adding the macros to `impl` methods is also not yet supported, those have to be
top-level functions due to the global generation of the `Tool` trait impl
```