---
title: Features
description: Every feature listed here is implemented at compile time by the Roslyn source generator. No reflection runs at runtime. No separate tooling step is required...
url: https://docs-v3-preview.elastic.dev/argh/features
---

# Features
Every feature listed here is implemented at compile time by the Roslyn source generator. No reflection runs at runtime. No separate tooling step is required.

## Code generation

[**Source-generated**](https://docs-v3-preview.elastic.dev/argh/features/source-generated) - The generator emits typed dispatch, parsers, help printers, and completion tables directly into your assembly. You can read, debug, and step through the generated code.
[**AOT and trimming safe**](https://docs-v3-preview.elastic.dev/argh/features/aot) - Zero reflection means your CLI publishes cleanly with Native AOT or the IL trimmer. No special configuration needed.

## Help and discovery

[**XML docs are your help text**](https://docs-v3-preview.elastic.dev/argh/features/help) - Write `<summary>`, `<param>`, `<remarks>`, and `<example>` once on your handler methods. They appear in `--help` automatically.
[**Shell completions**](https://docs-v3-preview.elastic.dev/argh/features/completions) - Tab completion for commands, namespaces, and flags. One install command for bash, zsh, or fish.
[**Fuzzy matching**](https://docs-v3-preview.elastic.dev/argh/features/fuzzy-matching) - Typos produce actionable error messages with the correct qualified command path and a `--help` suggestion.

## Data and validation

[**DataAnnotations validation**](https://docs-v3-preview.elastic.dev/argh/features/validation) - Standard .NET validation attributes (`[Range]`, `[StringLength]`, `[AllowedValues]`, `[Existing]`) generate inline checks. Constraints appear in help output.
[**DTO binding**](https://docs-v3-preview.elastic.dev/argh/features/dto-binding) - Annotate a record or class with `[AsParameters]` to expand its members into individual CLI flags. Supports prefixes and inheritance.

## Schema and tooling

[**Agent-ready JSON schema**](https://docs-v3-preview.elastic.dev/argh/features/schema) - `myapp __schema` emits a full JSON description of your CLI conforming to [cli-schema v1](https://github.com/cli-schema/cli-schema). Feed it to LLMs, generate docs, or diff in CI.

## Runtime behavior

[**Middleware**](https://docs-v3-preview.elastic.dev/argh/features/middleware) - Cross-cutting concerns (timing, auth, logging) live in `ICommandMiddleware` implementations. Wire them globally or per-command with `[MiddlewareAttribute<T>]`.
[**Cancellation**](https://docs-v3-preview.elastic.dev/argh/features/cancellation) - Add `CancellationToken` to any handler signature. It tracks Ctrl+C in console apps, or links to host shutdown with `Nullean.Argh.Hosting`.