Struct FnTool 

pub struct FnTool { /* private fields */ }

A Tool built from a plain async function.

Use this to adapt an Autumn handler’s core logic:

async fn get_weather(input: Value) -> Result<Value, AgentError> {
    let city = input["city"].as_str().unwrap_or("unknown");
    Ok(json!({"city": city, "temp_f": 72}))
}

let tool = FnTool::new(
    "get_weather",
    "Current weather for a city.",
    serde_json::json!({
        "type": "object",
        "properties": {"city": {"type": "string"}},
        "required": ["city"],
    }),
    get_weather,
);

Implementations

impl FnTool

pub fn new<F, Fut>( name: impl Into<String>, description: impl Into<String>, schema: Value, run: F, ) -> Self

where F: Fn(Value) -> Fut + Send + Sync + 'static, Fut: Future<Output = Result<Value, AgentError>> + Send + 'static,

Wrap an async function as a tool.

The function receives the decoded JSON arguments and returns JSON. Return ErrorKind::Tool errors for domain failures so the agent loop reports them back to the model instead of aborting the run.

pub fn with_context<F, Fut>( name: impl Into<String>, description: impl Into<String>, schema: Value, run: F, ) -> Self

where F: Fn(Value, ToolContext) -> Fut + Send + Sync + 'static, Fut: Future<Output = Result<Value, AgentError>> + Send + 'static,

Wrap an async function that also wants the ToolContext.

Use it when the tool needs the run id or call id, for example as an idempotency key.

pub const fn effect(self, effect: ToolEffect) -> Self

Declare what the tool can change. The default is ToolEffect::Write.

pub fn shared(self) -> Arc<dyn Tool>

Share the tool between the plugin registry and direct use.

Trait Implementations

impl Debug for FnTool

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Tool for FnTool

fn name(&self) -> &str

Tool name as the model calls it. Keep it snake_case.

fn description(&self) -> &str

What the tool does, shown to the model.

fn input_schema(&self) -> Value

JSON Schema for the tool’s input object.

fn execute<'a>( &'a self, input: Value, ctx: &'a ToolContext, ) -> Pin<Box<dyn Future<Output = Result<Value, AgentError>> + Send + 'a>>

Run the tool against decoded JSON arguments.

fn effect(&self) -> ToolEffect

What the tool can change. Defaults to ToolEffect::Write: a tool is trusted with less only when it says so.

fn definition(&self) -> ToolDefinition

Bundle the metadata the model sees into a ToolDefinition.