ai-native-cli

A specification for building command-line tools that AI agents can use safely and consistently. It defines rules for JSON output, inputs, errors, exit codes, safety checks, and explaining the tool's interface.

In plain words
What is it for?
Designing new command-line tools, adapting existing ones for agents, creating automation pipelines, and checking whether a CLI meets agent-safety requirements.
Why use it?
Agents need predictable machine-readable results and clear failure behavior to avoid misusing commands. The specification provides requirements that can be checked automatically.

Skill for Claude CodeCodex

Part of the agent-harness plugin — 35 skills, 9 commands, 12 agents shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/ghosteken/agent-harness/ai-native-cli
Any agent
npx skills add Ghosteken/agent-harness --skill ai-native-cli
Clone the repo
git clone --depth 1 https://github.com/Ghosteken/agent-harness

Made for: Claude Code, Codex.

Or install agent-harness, the plugin that ships this one along with the rest of its 35 skills, 9 commands, 12 agents.

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,549 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00044 $0.03549
Opus 5 $0.00022 $0.01775
Sonnet 5 $0.00009 $0.00710
Haiku 4.5 $0.00004 $0.00355

Measured 2d ago against content hash 2cb7fe77de1a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ai-native-cli scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to ai-native-cli — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

archive/skills-community/ai-native-cli/SKILL.md · 316 lines

How it starts

The opening of the file, as written. The whole thing — 316 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent-Friendly CLI Spec v0.1

When building or modifying CLI tools, follow these rules to make them safe and reliable for AI agents to use.

Overview

A comprehensive design specification for building AI-native CLI tools. It defines 98 rules across three certification levels (Agent-Friendly, Agent-Ready, Agent-Native) with prioritized requirements (P0/P1/P2). The spec covers structured JSON output, error handling, input contracts, safety guardrails, exit codes, self-description, and a feedback loop via a built-in issue system.

When to Use This Skill

  • Use when building a new CLI tool that AI agents will invoke
  • Use when retrofitting an existing CLI to be agent-friendly
  • Use when designing command-line interfaces for automation pipelines
  • Use when auditing a CLI tool's compliance with agent-safety standards

Core Philosophy

  1. Agent-first -- default output is JSON; human-friendly is opt-in via --human
  2. Agent is untrusted -- validate all input at the same level as a public API
  3. Fail-Closed -- when validation logic itself errors, deny by default
  4. Verifiable -- every rule is written so it can be automatically checked

Layer Model

This spec uses two orthogonal axes:

  • Layer answers rollout scope: core, recommended, ecosystem
  • Priority answers severity: P0, P1, P2

Use layers for migration and certification:

  • core -- execution contract: JSON, errors, exit codes, stdout/stderr, safety
  • recommended -- better machine UX: self-description, explicit modes, richer schemas
  • ecosystem -- agent-native integration: agent/, skills, issue, inline context

Certification maps to layers:

  • Agent-Friendly -- all core rules pass
  • Agent-Ready -- all core + recommended rules pass
  • Agent-Native -- all layers pass

How It Works

Step 1: Output Mode

Default is agent mode (JSON). Explicit flags to switch:

$ mycli list              # default = JSON output (agent mode)
$ mycli list --human      # human-friendly: colored, tables, formatted
$ mycli list --agent      # explicit agent mode (override config if needed)

Read the full file on GitHub · 316 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 316 lines · 44 tokens per session scan A 2cb7fe77de1a

Subscribe to this mod's changes

ai-native-cli is a skill published in the GitHub repository Ghosteken/agent-harness (2 stars, last pushed 17d ago), licensed MIT. It adds 44 tokens to every session and 3,549 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to ai-native-cli, differing in 0 lines, and is treated as a copy.