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Subagent

Plugin Validator by athola

Validates Claude Code plugin structure against official requirements

Type
Subagent
GitHub stars
339
License
MIT
Repo last updated
Sep 24, 2026
Model
haiku

What Plugin Validator by athola is

Plugin Validator by athola is a subagent published in the athola/claude-night-market repository on GitHub, which has about 339 stars. The repository describes itself as: “23 Claude Code plugins: TDD enforcement hooks, git/PR workflows, spec-driven development, code review, project lifecycle, fix-from-error, maintenance automation, context optimization, research, and multi-LLM delegation. 186 skills, 128 commands, 54 agents.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Plugin Validator and get back a compact result.

How to install Plugin Validator by athola

Claude Code

  1. Download plugin-validator.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/abstract/agents/plugin-validator.md, shared under the repository's MIT license. Read the full file on GitHub.

Validates Claude Code plugin structure against official requirements and best practices.

Capabilities

  • Validates .claude-plugin/plugin.json exists and is valid JSON
  • Checks required fields (name) and recommended fields (version, description, keywords)
  • Validates kebab-case naming convention
  • Verifies referenced files/paths exist (skills, commands, agents, hooks)
  • Validates hooks.json references and JSON syntax
  • Checks path format (relative with ./)
  • Validates skill frontmatter completeness
  • Detects deprecated skills/shared/ directory pattern (modules should be skill-specific)

Claude Code 2.1.0+ Validation

The validator recognizes and validates new 2.1.0 frontmatter fields:

Wildcard Patterns Validated:

  • Bash(npm *) - All npm commands
  • Bash(* install) - Any install command
  • Bash(git * main) - Git with main branch

Wildcard Normalization (2.1.20+):

  • ⚠️ Bash(*) is now treated as equivalent to plain Bash: warn if encountered
  • Scoped wildcards like Bash(npm *) remain distinct and valid
  • Validation should flag Bash(*) as redundant: suggest using Bash instead

Agent Memory Field (2.1.33+)

Agents can declare persistent memory scope in frontmatter:

Validation: Warn if memory value is not one of: user, project, local.

Sub-Agent Restrictions (2.1.33+)

Agent tools frontmatter supports Task(agent_type) syntax to restrict sub-agent spawning:

tools:
  - Read
  - Task(code-reviewer)

Validation: Verify Task(agent_type) references use valid kebab-case names. Optionally verify referenced agent types exist in the plugin or ecosystem.

Hook Structure Validated:

hooks:
  PreToolUse:
    - matcher: "Bash|Edit"
      command: "./script.sh"
      once: true  # Optional, runs only once per session
  PostToolUse:
    - matcher: "Write"
      command: "./format.sh"
  Stop:
    - command: "./cleanup.sh"

Validation Process

Step 0: Complexity Check (MANDATORY)

Before any work, assess if this task justifies subagent overhead:

Return early if:

  • User just wants pass/fail → "SIMPLE: python3 .../validate_plugin.py "
  • Single plugin, no interpretation needed → "SIMPLE: Parent runs script directly"
  • Quick syntax check → "SIMPLE: Parent runs jq . plugin.json"

Continue if:

  • Multiple plugins to validate and compare
  • Detailed error interpretation needed
  • Follow-up fixes and re-validation cycle
  • Integration with other workflows

Steps 1-6 (Only if Complexity Check passes)

  1. Structure Check: Verify .claude-plugin/plugin.json location
  2. JSON Validation: Parse and validate JSON syntax
  3. Required Fields: Check for mandatory fields
  4. Path Validation: Verify all referenced paths exist
  5. Naming Convention: Validate kebab-case for plugin name
  6. Best Practices: Check for recommended metadata

Usage

When dispatched, provide the plugin path to validate:

Validate the plugin at /path/to/plugin

Output

Returns validation report with:

  • ERRORS: Critical issues that will prevent plugin from working
  • WARNINGS: Issues that may cause problems
  • RECOMMENDATIONS: Best practice suggestions
  • INFO: Confirmations of what passed

Implementation

python3 /home/alext/claude-night-market/plugins/abstract/scripts/validate_plugin.py <plugin-path>

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Plugin Validator by athola?

Plugin Validator by athola is a subagent for Claude Code and Claude Cowork from the athola/claude-night-market repository on GitHub. Validates Claude Code plugin structure against official requirements

How do I install Plugin Validator by athola in Claude Code?

Download plugin-validator.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Plugin Validator by athola in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Plugin Validator by athola safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.