# Claude Code: Skills

## Metadata

| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | cap-protocol |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | Claude Code: Skills |
| Source URL | https://code.claude.com/docs/en/skills |
| Source publisher / author | Anthropic |
| Source type | vendor docs |
| Source date (published) | Unknown — not stated |
| Date researched | 2026-10-25 |
| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
| Research method | direct page fetch |
| Confidence | Medium |
| Status | Active |

## Summary

Claude Code's skills documentation: loading, frontmatter, model pinning, forked subagent context and size guidance. Only the first 100000 of 118114 characters were read.

## Key findings

- Skill descriptions are loaded into context so the model knows what exists; the body loads only when invoked, so long reference material 'costs almost nothing until you need it'.
- Frontmatter includes `description`, `when_to_use`, `disable-model-invocation`, `user-invocable`, `allowed-tools`, `model` (applies for the rest of the current turn), `effort`, `context: fork` (run in an isolated subagent), `agent`, `background`.
- Combined `description` plus `when_to_use` is truncated at 1,536 characters in the listing; keep the body under 500 lines; after compaction re-attached skills share a 25,000-token budget and keep their first 5,000 tokens.
- `context: fork` skills do not see the conversation history, so their instructions must stand on their own.
- Create a skill 'when you keep pasting the same instructions, checklist, or multi-step procedure into chat'.
- Custom commands have been merged into skills.

## Pros / strengths

Shows a skill can both carry guidance and pin the model or fork a subagent for its own run.

## Cons / limitations / caveats

Tail unread; some fields are product-specific and not part of the open Agent Skills format.

## Relevance to tai

Supports the split 'tool does the action, skill teaches when and how': a skill carries a recurring procedure at near-zero idle cost, but enforces nothing by itself.

## Changelog

| Date | Change |
|---|---|
| 2026-10-25 | Initial dossier created. |