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metaschema-basics

metaschema-basics is a skill for Claude Code from metaschema-framework/claude-plugins. It costs 23 tokens per session (608 once invoked), scanned A, original, CC0-1.0.

An introduction to Metaschema, a framework for defining data models and generating XML and JSON schemas from one source. It also explains data structures, types, and validation rules.

In plain words
What is it for?
Use it to learn Metaschema fundamentals, including modules, assemblies, fields, flags, data types, cardinality, and constraints.
Why use it?
It gives newcomers the basic concepts needed to understand Metaschema files and directs them to more specific guidance when they need to create modules or rules.

Skill for Claude Code

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

Part of the metaschema plugin — 4 skills shipped together

not rated 10repo 8mo ago A scan 23 tokens original CC0-1.0

Good fit Use it to learn Metaschema fundamentals, including modules, assemblies, fields, flags, data types, cardinality, and constraints.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/metaschema-framework/claude-plugins/metaschema-basics
View source ↗ metaschema-framework/claude-plugins
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 metaschema-framework/claude-plugins --skill metaschema-basics
Clone the repo
git clone --depth 1 https://github.com/metaschema-framework/claude-plugins

Made for: Claude Code.

Or install metaschema, the plugin that ships this one along with the rest of its 4 skills.

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 metaschema-basics

README.md
[![agentmods](https://agentmods.dev/badge/skills/metaschema-framework/claude-plugins/metaschema-basics/github.svg)](https://agentmods.dev/skills/metaschema-framework/claude-plugins/metaschema-basics)
Your own site
<a href="https://agentmods.dev/skills/metaschema-framework/claude-plugins/metaschema-basics"><img src="https://agentmods.dev/badge/skills/metaschema-framework/claude-plugins/metaschema-basics/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 metaschema-basics

Your own site · 80×15
<a href="https://agentmods.dev/skills/metaschema-framework/claude-plugins/metaschema-basics"><img src="https://agentmods.dev/badge/skills/metaschema-framework/claude-plugins/metaschema-basics.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 608 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.
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 $0.00023 $0.00608
Opus 5.5 $0.00009 $0.00243
Sonnet 5.5 $0.00005 $0.00122
Haiku 4.5 $0.00002 $0.00061

Measured 2mo ago against content hash 80b1daf04b7f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

metaschema-basics 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 2mo 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/metaschema/skills/metaschema-basics/SKILL.md · 71 lines

How it starts

The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Metaschema Basics

Metaschema is an information modeling framework that allows defining data models in a format-agnostic way, generating XML and JSON schemas from a single source, and specifying constraints and validation rules.

Core Concepts

Module

A Metaschema file defining a model or portion of a model. Modules can import other modules.

→ For details: See metaschema-module-authoring skill (creating or understanding modules)

Definition Types

Type Description Example
Assembly Complex structure containing fields and other assemblies catalog, control, metadata
Field Simple data element with a typed value title, description, email
Flag Attribute/property on an assembly or field id, uuid, class

→ For details: See metaschema-module-authoring skill (structure, data types, cardinality)

Constraints

Validation rules applied to data instances:

  • allowed-values - Enumerated value sets
  • expect - Assertions that must be true
  • matches - Regex and datatype validation
  • has-cardinality - Occurrence count rules
  • index / index-has-key - Cross-reference validation
  • is-unique - Uniqueness enforcement

→ For details: See metaschema-constraints-authoring skill (creating or understanding constraints)

Metapath

XPath 3.1-based expression language for navigating and querying Metaschema data:

./control[@id = 'AC-1']              # Find control by ID
.//param[exists(./value)]            # Find params with values
ancestor::catalog/metadata/title     # Navigate to catalog title

→ For details: See metapath-expressions skill (syntax, operators, functions)

Data Formats

Metaschema supports three equivalent serialization formats:

  • XML (.xml)
  • JSON (.json)
  • YAML (.yaml)

A model defined in Metaschema can parse and serialize to any of these formats.

When to Use Which Skill

Task Skill
Understanding or writing modules metaschema-module-authoring
Understanding or writing constraints metaschema-constraints-authoring
Understanding or writing Metapath expressions metapath-expressions
Quick conceptual overview (you are here) metaschema-basics

Read the full file on GitHub · 71 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. 2mo ago First seen · 71 lines · 23 tokens per session scan A 80b1daf04b7f

Subscribe to this mod's changes

metaschema-basics is a skill published in the GitHub repository metaschema-framework/claude-plugins (10 stars, last pushed 8mo ago), licensed CC0-1.0. It adds 23 tokens to every session and 608 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.

Learning and teaching
Related

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metaschema-basics next to 6 skills from other repositories
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metaschema-basicsmetaschema-framework/claude-pluginsSkill108mo agoCC0-1.0A23Claude Code
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