validate-plugin

validate-plugin is a skill for Claude Code from tmchow/tmc-marketplace. It costs 11 tokens per session (634 once invoked), scanned A, original, MIT.

A checker for validating the structure and manifest files of coding-agent plugins before they are published. It checks required folders, metadata, JSON syntax, and skill documentation.

In plain words
What is it for?
Use it to validate one plugin or all plugins, including required files, names, versions, descriptions, authors, skill paths, and skill instruction headers.
Why use it?
Small packaging or metadata mistakes can stop a plugin from being recognised or installed correctly. Validation catches these issues before the plugin reaches a marketplace.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions Claude Code.

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/tmchow/tmc-marketplace/validate-plugin
Any agent
npx skills add tmchow/tmc-marketplace --skill validate-plugin
Clone the repo
git clone --depth 1 https://github.com/tmchow/tmc-marketplace

Made for: Claude Code.

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 validate-plugin

README.md
[![agentmods](https://agentmods.dev/badge/skills/tmchow/tmc-marketplace/validate-plugin.svg)](https://agentmods.dev/skills/tmchow/tmc-marketplace/validate-plugin)
Your own site
<a href="https://agentmods.dev/skills/tmchow/tmc-marketplace/validate-plugin"><img src="https://agentmods.dev/badge/skills/tmchow/tmc-marketplace/validate-plugin.svg" alt="Measured on agentmods" height="20"></a>
Per session 11 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 634 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00011 $0.00634
Opus 5 $0.00005 $0.00317
Sonnet 5 $0.00002 $0.00127
Haiku 4.5 $0.00001 $0.00063

Measured 6d ago against content hash f0491b6e03c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

validate-plugin 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 6d 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.

.claude/skills/validate-plugin/SKILL.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plugin Validator

Validate a plugin meets marketplace requirements before publishing.

Usage

/validate-plugin <plugin-name>

Or validate all plugins:

/validate-plugin --all

Validation Checks

1. Plugin Structure

# Check required files exist
ls plugins/<plugin-name>/.claude-plugin/plugin.json
ls plugins/<plugin-name>/README.md
ls plugins/<plugin-name>/skills/  # At least skills/ or agents/ must exist

2. plugin.json Validation

Required fields:

  • name - must match directory name
  • version - semver format (e.g., "0.1.0")
  • description - non-empty string
  • author.name - non-empty string
  • skills - path to skills directory (if skills exist)
  • agents - path to agents directory (if agents exist)
# Validate JSON syntax
cat plugins/<plugin-name>/.claude-plugin/plugin.json | jq .

3. Skill Validation

For each plugins/<plugin-name>/skills/*/SKILL.md:

Required frontmatter:

---
name: skill-name        # Required
description: ...        # Required - when Claude should use this
---

Optional frontmatter:

disable-model-invocation: true   # User-only skill
user-invocable: false            # Claude-only skill

Check: Frontmatter must be valid YAML between --- markers

4. Agent Validation

For each plugins/<plugin-name>/agents/*/AGENT.md:

Required frontmatter:

---
name: agent-name        # Required
description: ...        # Required - when Claude should use this agent
---

5. Marketplace Registry

Check .claude-plugin/marketplace.json contains entry:

{
  "plugins": [
    {
      "name": "<plugin-name>",
      "source": "./plugins/<plugin-name>",
      "description": "...",
      "version": "..."
    }
  ]
}

6. No Deprecated Commands

Verify no commands/ directory exists (commands merged into skills in Claude Code 2.1.3+)

Output Format

Validating plugin: <plugin-name>

[PASS] Plugin structure valid
[PASS] plugin.json valid
[PASS] 2 skills validated
[WARN] No agents defined (optional)
[PASS] Marketplace entry found
[PASS] No deprecated commands

Result: VALID (5 passed, 1 warning, 0 errors)

Read the full file on GitHub · 125 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. 6d ago First seen · 125 lines · 11 tokens per session scan A f0491b6e03c9

Subscribe to this mod's changes

validate-plugin is a skill published in the GitHub repository tmchow/tmc-marketplace (22 stars, last pushed 6mo ago), licensed MIT. It adds 11 tokens to every session and 634 once invoked, about $0.0001 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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