Trait ToolValidator 

pub trait ToolValidator: Send + Sync {
    // Required method
    fn validate(&self, args: &Value) -> Result<(), AgentRuntimeError>;
}

Declarative argument validator for a ToolSpec.

Implement this trait to enforce custom argument constraints (type ranges, string patterns, etc.) before the handler is invoked.

Validators run after required_fields checks and before the handler. The first failing validator short-circuits execution.

Basic Example

use llm_agent_runtime::agent::ToolValidator;
use llm_agent_runtime::AgentRuntimeError;
use serde_json::Value;

struct NonEmptyQuery;
impl ToolValidator for NonEmptyQuery {
    fn validate(&self, args: &Value) -> Result<(), AgentRuntimeError> {
        let q = args.get("q").and_then(|v| v.as_str()).unwrap_or("");
        if q.is_empty() {
            return Err(AgentRuntimeError::AgentLoop(
                "tool 'search': q must not be empty".into(),
            ));
        }
        Ok(())
    }
}

Advanced Example — Parameterised validator

use llm_agent_runtime::agent::{ToolSpec, ToolValidator};
use llm_agent_runtime::AgentRuntimeError;
use serde_json::Value;

/// Validates that a named integer field is within [min, max].
struct RangeValidator { field: &'static str, min: i64, max: i64 }

impl ToolValidator for RangeValidator {
    fn validate(&self, args: &Value) -> Result<(), AgentRuntimeError> {
        let n = args
            .get(self.field)
            .and_then(|v| v.as_i64())
            .ok_or_else(|| {
                AgentRuntimeError::AgentLoop(format!(
                    "field '{}' must be an integer", self.field
                ))
            })?;
        if n < self.min || n > self.max {
            return Err(AgentRuntimeError::AgentLoop(format!(
                "field '{}' = {n} is outside [{}, {}]",
                self.field, self.min, self.max,
            )));
        }
        Ok(())
    }
}

// Attach to a tool spec:
let spec = ToolSpec::new("roll_dice", "Roll n dice", |args| {
    serde_json::json!({ "result": args })
})
.with_validators(vec![
    Box::new(RangeValidator { field: "n", min: 1, max: 100 }),
]);

Required Methods

fn validate(&self, args: &Value) -> Result<(), AgentRuntimeError>

Validate args before the tool handler is invoked.

Return Ok(()) if the arguments are valid, or Err(AgentRuntimeError::AgentLoop(...)) with a human-readable message.

Implementors