claude.ai plugin Directory silently drops a skill whose SKILL.md `description` contains <> or [] characters

Summary

When a plugin bundles multiple skills via the standard skills/<name>/SKILL.md layout, the claude.ai plugin Directory (Settings → Plugins) silently omits any skill whose frontmatter description contains angle or square brackets (<…>, […]). The skill is dropped from the plugin's Skills inventory — nothing appears in an Errors tab or as a warning. The Claude Code CLI loads the same skill fine from the same commit.

Environment

• Surface: claude.ai → Settings → Plugins (the plugin "Directory"), 2026-07-13
• Marketplace added via Add → Add from a repository (git URL) → Sync
• Reproduced in a clean, freshly created Chrome profile (rules out any client/install cache)

Steps to reproduce

1. Use a plugin with two skills: skills/now/SKILL.md (plain-text description) and skills/resume/SKILL.md whose description contains <X> and [name].
2. In claude.ai → Plugins → Add → Add from a repository, paste the git URL and Sync.
3. Open the plugin's detail in the Directory and read the Skills list.

Expected: Skills 2 — /now and /resume.
Actual: Skills 1 — /now only. /resume is absent, with no error surfaced anywhere.

Isolation (single variable)

• The two SKILL.md files are otherwise structurally identical (valid YAML frontmatter: description + allowed-tools).
• The only content difference was the brackets in resume's description. Rewriting it to plain text (removing <X> and [name]) and re-syncing made the Directory immediately show Skills 2. Nothing else changed.
• Not a per-plugin skill limit: the Anthropic Productivity plugin shows 4 skills in the same Directory.
• The marketplace's "Synced commit" confirmed the synced commit contained both SKILL.md files; the Claude Code CLI loads both from that commit.

Public reproduction

Repo: https://gitlab.com/recoursellm-group/skills.git, plugin kd-handoff

• Bug present at commit 308ee9e — resume's description contains <X> / [name] → Directory shows Skills 1.
• Fixed at commit c86e798 — brackets removed → Directory shows Skills 2.

Impact

Plugin authors ship silently incomplete plugins on claude.ai: skills that exist in the repo and work on the CLI simply don't appear, with no diagnostic. Bracket placeholders in descriptions (<name>, <topic>, [optional]) are common.

Suggested fix

Sanitize/escape description content when indexing skills rather than dropping the skill; or, if a skill fails validation, surface it in the plugin's Errors tab instead of silently omitting it.