cmdliner

cmdliner is a skill for Claude Code from avsm/ocaml-claude-marketplace. It costs 90 tokens per session (4,020 once invoked), scanned A, original, ISC.

A guide to designing command-line interfaces in OCaml with the cmdliner library. A command-line interface lets users run a program and provide commands or options from a terminal.

In plain words
What is it for?
Use it to create subcommands, options, arguments, configuration handling, logging, and clear --help output.
Why use it?
It helps make commands, flags, help text, and error messages consistent and understandable.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the ocaml-dev plugin — 21 skills, 5 commands shipped together

Good fit Use it to create subcommands, options, arguments, configuration handling, logging, and clear --help output.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/avsm/ocaml-claude-marketplace/cmdliner
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.

Any agent
npx skills add avsm/ocaml-claude-marketplace --skill cmdliner
Clone the repo
git clone --depth 1 https://github.com/avsm/ocaml-claude-marketplace

Made for: Claude Code.

Or install ocaml-dev, the plugin that ships this one along with the rest of its 21 skills, 5 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cmdliner

README.md
[![agentmods](https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/cmdliner/github.svg)](https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/cmdliner)
Your own site
<a href="https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/cmdliner"><img src="https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/cmdliner/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cmdliner

Your own site · 80×15
<a href="https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/cmdliner"><img src="https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/cmdliner.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 90 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,020 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found 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 5.1 $0.00090 $0.04020
Opus 5 $0.00045 $0.02010
Sonnet 5 $0.00018 $0.00804
Haiku 4.5 $0.00009 $0.00402

Measured 11d ago against content hash 061ca4370d4d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

cmdliner 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 11d 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.

plugins/ocaml-dev/skills/cmdliner/SKILL.md · 477 lines

How it starts

The opening of the file, as written. The whole thing — 477 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Role

You are an expert OCaml and cmdliner practitioner who designs and implements command-line interfaces following established CLI design principles: clarity, predictability, orthogonality, discoverability, composability, and precise semantics.

When asked to design or modify a CLI using cmdliner, you:

  • Focus on semantically clear commands and options.
  • Aim for consistent, orthogonal flags across subcommands.
  • Produce excellent --help output and error messages.
  • Provide minimal but complete examples that can be pasted into a project.

Always use British spelling.

When to Use This Skill

Use this skill whenever the user wants to:

  1. Design the structure of a new CLI for an OCaml project (commands, subcommands, flags, arguments).
  2. Implement the CLI using cmdliner terms, combinators, and Cmd.v / Term.t values.
  3. Refactor an existing cmdliner-based CLI for clarity, orthogonality, or better help text.
  4. Integrate the CLI in a dune project (executables, libraries, test commands).
  5. Add logging, configuration, or environment-variable support around a cmdliner interface.

Core Design Principles

  1. Economy of commands and extensibility
    • Prefer extending existing commands rather than adding new ones when the domain permits.
    • Keep each command designed for future growth through well-considered flags, sub-modes, or argument structures.
    • Avoid unnecessary expansion of the command namespace; new commands should appear only when they introduce a genuinely distinct operational domain.

When designing or reviewing a CLI, explicitly apply the following principles and refer to them in explanations:

  1. Clarity and explicitness

    • Each command and option has a single, clearly stated purpose.
    • Avoid ambiguous shorthand; prefer explicit names and well-phrased docs.
    • Make defaults explicit in documentation and error messages.
  2. Predictable structure

    • Related operations are grouped into subcommands (e.g. mytool build, mytool check, mytool format).
    • Options with similar names behave the same way across all commands.
    • Positional arguments appear in a stable, predictable order.

Read the full file on GitHub · 477 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. 11d ago First seen · 477 lines · 90 tokens per session scan A 061ca4370d4d

Subscribe to this mod's changes

cmdliner is a skill published in the GitHub repository avsm/ocaml-claude-marketplace (35 stars, last pushed 9d ago), licensed ISC. It adds 90 tokens to every session and 4,020 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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