# Skill Index > Use when deciding which of 50+ installed skills to invoke. Reads a compact one-line-per-skill index to identify ALL relevant skills in one operation instead of invoking each individually. - **Type:** Skill - **Install:** `agentstack add skill-niborracho-skill-index-skill-index` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [NiBorracho](https://agentstack.voostack.com/s/niborracho) - **Installs:** 0 - **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [NiBorracho](https://github.com/NiBorracho) - **Source:** https://github.com/NiBorracho/skill-index/tree/main/skill-index ## Install ```sh agentstack add skill-niborracho-skill-index-skill-index ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Skill Index ## Overview **Problem:** With 150+ installed skills, finding the right one by invoking each individually takes ~12.5 minutes (150 × 5s/call). The `Skill` tool loads full content even when you only need the 1-2 line description. **Solution:** A compact `INDEX.md` file (~15KB for 150 skills) that Claude reads in one `Read` tool call, then identifies and invokes **all** relevant skills — no limit. **Impact:** ~12.5 min → ~15 seconds to identify and load the right skills. --- ## When to Use | Situation | Action | |-----------|--------| | Choosing which skills to invoke (50+ installed) | Read INDEX.md first | | After installing a new skill | Run `build-index.sh update` | | After removing a skill | Run `build-index.sh remove ` | | Index missing or corrupted | Run `build-index.sh build` | | Debugging skill discovery | Run `build-index.sh debug` | **Do NOT** invoke skills blindly before reading the index when you have 50+ skills available. --- ## Querying the Index ``` 1. Read("~/.claude/skills/skill-index/INDEX.md") 2. Scan for entries matching keywords from the current task 3. Identify ALL relevant skills (no maximum — invoke every one that applies) 4. Skip entries marked as ~~deprecated~~ 5. Invoke identified skills with the Skill tool ``` Reading the index costs 1 `Read` operation. Invoke as many skills as the task requires. --- ## Index File Format Location: `~/.claude/skills/skill-index/INDEX.md` Each skill entry uses HTML comment markers for reliable, auditable parsing: ```markdown - **skill-name** [source@version] — description from frontmatter ``` - **Markers** guarantee idempotent updates (each `add`/`remove` targets exactly one block) - **SHA256** detects when a skill file changes between sessions - **Deprecated entries** use strikethrough: `~~**skill-name**~~` - **Sections** group skills by source plugin for readability The file also contains metadata blocks: ```markdown ``` and an audit block at the end: ```markdown ``` --- ## Installation & Passive Setup Run once after installing this skill: ```bash # Linux / Mac / WSL bash ~/.claude/skills/skill-index/scripts/install-hooks.sh # Windows PowerShell & "$env:USERPROFILE\.claude\skills\skill-index\scripts\install-hooks.sh" # or use the PowerShell installer: powershell -File "$env:USERPROFILE\.claude\skills\skill-index\scripts\build-index.ps1" install-hooks ``` This adds a `SessionStart` hook to `~/.claude/settings.json` that runs `build-index.sh update --quiet` on every session start. The update operation: - Compares `installed_plugins.json` hash against the last recorded hash - Only re-scans if plugins changed ( ` | Register a specific skill by path | | `build-index.sh remove ` | Remove skill from index | | `build-index.sh deprecate ""` | Mark skill as deprecated | | `build-index.sh verify` | Validate checksums and integrity | | `build-index.sh query ""` | Search index (outputs matches to stdout) | | `build-index.sh debug` | Full diagnostic: paths scanned, errors, stats | PowerShell equivalent: `build-index.ps1 [args]` — identical interface. --- ## Scanned Locations The scripts search for `SKILL.md` files in: ``` ~/.claude/plugins/cache/*/[plugin]/[version]/skills/*/SKILL.md ~/.claude/plugins/cache/*/[plugin]/[version]/.agents/skills/*/SKILL.md ~/.claude/skills/*/SKILL.md ~/.agents/skills/*/SKILL.md ``` Skills missing a valid `name` or `description` in frontmatter are logged as `E001` errors and skipped. --- ## Error Codes | Code | Cause | Remedy | |------|-------|--------| | `E001` | SKILL.md missing `name` or `description` in frontmatter | Fix the skill's frontmatter | | `E002` | Duplicate skill name, different paths | Check for conflicting plugins | | `E003` | INDEX.md not found | Run `build` to create it | | `E004` | SHA256 not available — CRC32 fallback active (integrity weakened) | Install `sha256sum` or `shasum` | | `E005` | Plugin path in `installed_plugins.json` not found on disk | Reinstall the plugin | All errors are written to `~/.claude/skills/skill-index/audit.log` with timestamp and error code. --- ## Audit Log Every operation appends to `audit.log`: ``` 2026-04-23T14:00:00Z BUILD full_scan total=152 duration=4.2s 2026-04-23T14:05:00Z ADD brainstorming v5.0.7 sha256:abc123 2026-04-23T14:06:00Z REMOVE old-skill v1.0.0 2026-04-23T15:00:00Z UPDATE api-design v1.9.0→v2.0.0 2026-04-23T15:01:00Z DEPRECATE legacy-skill reason="replaced by new-skill" 2026-04-23T15:02:00Z VERIFY integrity=valid total=153 changed=1 2026-04-23T16:00:00Z ERROR E001 path=... missing=description ``` The audit log is append-only and never modified by the scripts — safe for external monitoring (socket.dev, Snyk, CI pipelines). --- ## Security & Auditability - **No external dependencies** — pure bash + PowerShell built-ins only - **No network calls** — filesystem operations only - **No elevated privileges** — writes only to `~/.claude/skills/skill-index/` - **Reproducible** — same filesystem state always produces the same INDEX.md - **Auditable format** — plain markdown + HTML comments readable by any tool - **socket.dev / Snyk compatible** — nothing to scan (zero package dependencies) --- ## Common Mistakes | Mistake | Correct behavior | |---------|-----------------| | Invoking skills without reading the index first | Always `Read(INDEX.md)` before invoking | | Stopping after finding 1 relevant skill | Invoke ALL skills that match the task | | Using deprecated entries | Skip `~~strikethrough~~` entries | | Forgetting to run `install-hooks.sh` | The passive hook only works after setup | | Manually editing INDEX.md | Always use the scripts — manual edits break checksums | ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [NiBorracho](https://github.com/NiBorracho) - **Source:** [NiBorracho/skill-index](https://github.com/NiBorracho/skill-index) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-niborracho-skill-index-skill-index - Seller: https://agentstack.voostack.com/s/niborracho - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.