Struct ToolDefinition 

pub struct ToolDefinition {
    pub tool: Box<dyn AgentTool>,
    pub snippet: &'static str,
    pub guidelines: &'static [&'static str],
    pub prepare_arguments: Option<fn(Value) -> Result<Value, String>>,
    pub before_tool_call: Option<fn(&Value) -> Option<BeforeToolCallResult>>,
    pub after_tool_call: Option<fn(&ToolResult, bool) -> Option<AfterToolCallResult>>,
    pub renderer: Option<Arc<dyn ToolRenderer>>,
}

A tool bundled with its prompt metadata.

Mirrors pi’s ToolDefinition which carries promptSnippet, promptGuidelines and prepareArguments directly on the tool definition.

Fields

tool: Box<dyn AgentTool>

snippet: &'static str

One-line snippet for the “Available tools” section of the system prompt.

guidelines: &'static [&'static str]

Guideline bullets for the “Guidelines” section of the system prompt.

prepare_arguments: Option<fn(Value) -> Result<Value, String>>

Optional pre-processing of raw LLM arguments before execute(). Receives raw arguments, returns normalized arguments or an error message.

before_tool_call: Option<fn(&Value) -> Option<BeforeToolCallResult>>

Called before tool execution, after argument validation (matching pi’s beforeToolCall). Return Some(BeforeToolCallResult { block: true, reason: "..." }) to block execution.

after_tool_call: Option<fn(&ToolResult, bool) -> Option<AfterToolCallResult>>

Called after tool execution, before the result is returned (matching pi’s afterToolCall).

renderer: Option<Arc<dyn ToolRenderer>>

Tool-specific renderer for the TUI, bundled with the tool definition (pi’s renderCall/renderResult live on ToolDefinition).

Trait Implementations

impl AgentTool for ToolDefinition

fn name(&self) -> &str

Unique tool name (used in LLM tool_use)

fn label(&self) -> &str

Human-readable label for UI

fn description(&self) -> &str

Description for the LLM

fn parameters_schema(&self) -> Value

JSON Schema for parameters

fn execute<'life0, 'async_trait>( &'life0 self, params: Value, ctx: ToolContext, ) -> Pin<Box<dyn Future<Output = Result<ToolResult, ToolError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Execute the tool.