Crate neuron_tool_macros 

neuron-tool-macros

Procedural macro crate for the neuron tool system. Provides the #[neuron_tool] attribute macro that generates a full Tool trait implementation from an annotated async function, eliminating boilerplate for tool definitions.

Installation

cargo add neuron-tool-macros

Or use it through neuron-tool with the macros feature (enabled by default).

What It Generates

Given an async function, the macro generates:

• An Args struct (e.g., CalculateArgs) with Deserialize and JsonSchema derives
• A zero-sized Tool struct (e.g., CalculateTool)
• A Tool trait implementation with the function body as call()
• A ToolDefinition with the JSON Schema derived from the args struct via schemars

Field doc comments (///) on function parameters are preserved as schema descriptions.

Key Attributes

• name (required) – the tool name string used in LLM tool calls
• description (required) – human-readable description of what the tool does

Usage

use neuron_tool_macros::neuron_tool;
use neuron_types::ToolContext;

#[neuron_tool(name = "calculate", description = "Evaluate a math expression")]
async fn calculate(
    /// A mathematical expression like "2 + 2"
    expression: String,
    _ctx: &ToolContext,
) -> Result<CalculateOutput, CalculateError> {
    let result = eval(&expression)?;
    Ok(CalculateOutput { result })
}

// The macro generates:
// - `CalculateArgs { expression: String }` with Deserialize + JsonSchema
// - `CalculateTool` (zero-sized struct)
// - `impl Tool for CalculateTool` with NAME = "calculate"
//
// Register the generated tool:
// registry.register(CalculateTool);

The last parameter must be &ToolContext (or _ctx: &ToolContext if unused). All preceding parameters become fields on the generated args struct. The return type must be Result<Output, Error> where both types are concrete.

The struct names are derived from the function name converted to PascalCase: calculate produces CalculateTool and CalculateArgs, read_file produces ReadFileTool and ReadFileArgs.

This macro is re-exported from neuron-tool when the macros feature is enabled: neuron_tool::neuron_tool.

Part of neuron

This crate is part of neuron, a composable building-blocks library for AI agents in Rust.

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

Attribute Macros

neuron_tool

Derive a Tool implementation from an async function.