Agent Skill Management

Agent Skill Management

Use this capability to manage agent skills in a two-tier project, or to verify and diagnose their discovery and active loading. Management includes adding, editing, renaming, moving, and removing skills. Distributable skills — portable capabilities other projects can install — are authored in a source directory (conventionally skills/, the source of truth) and installed into the skill root (the directory the agent actually loads — .claude/skills/ for Claude Code, .agents/skills/ for Codex and several others) with the vercel-labs/skills CLI (npx skills); a skills-lock.json file records what was installed. Repository-local skills — capabilities that encode a single project's own process and have to fire while a surface is being edited, never a document the project's own instructions could route to on demand — are committed directly under the skill root and are never touched by the CLI.

Discovery is what routes to a skill in either tier: each skill advertises when it applies through its own description, so no written index is required. Some hosts maintain one anyway (e.g. an AGENTS.md table), which then becomes a second record to keep current.

This skill is self-contained: it names no repository-specific file or layout and references no repository-root index, so it works installed on its own. The directory names below are the conventional defaults — skills/ for the source, and a skill root of .claude/skills/ on Claude Code or .agents/skills/ on Codex. Substitute the host project's chosen paths where they differ, and note that a project targeting both hosts has two roots, one of which may be a symlink into the other.

Guidelines:

• MUST, where the host project maintains a written skill index, keep it in sync whenever a skill in either tier is added, renamed, moved, or removed, per your project's skill-authoring conventions; where it maintains none, each skill's description frontmatter is the whole of discovery and no index is owed.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

Is the Material a Skill?

Before asking which tier a skill belongs in, ask whether the material should be a skill at all. A skill's one functional advantage over a document is discovery — it fires unasked while a matching surface is being edited, without anyone remembering to consult it — and that advantage is also its whole recurring cost: every skill's description competes for room in every session's listing, on every task, whether or not that task needs it. Material that never has to fire unasked pays that cost for nothing, because an always-loaded instruction file can route to it on demand instead.

The portability question below cannot make this call. A repository-layout document is exactly as unportable as a repository-layout skill, so portability returns "no" for both — asking it first leaves a reader concluding the material must be a repository-local skill, having never asked whether it should be a skill in the first place.

Guidelines:

• MUST answer this question before Choosing a Tier, for new material and for material a change is about to add to an existing skill.
• MUST NOT write a skill for material an always-loaded instruction file can already route to on demand; that routing costs one line there and nothing in every other session's listing.
• MUST retire an existing skill into documentation when this question reclassifies it — move its content into the project's own living documentation or its contributor documentation, and remove the skill rather than leaving both in place.

Choosing a Tier

Every skill lives in exactly one tier, decided by one question: would the skill work, unchanged, installed into another project?

• A skill that is self-contained and portable — it names no repository-specific file, workflow, or layout — is distributable: author it under the source directory (skills/<name>/) and install it with the CLI.
• A skill that encodes one project's own process as a capability — the skill-authoring rules a project tailors to itself, a project's own change loop, a review policy written against its own diffs — is repository-local: commit it directly under the skill root (.claude/skills/<name>/, or .agents/skills/<name>/ on a host that reads that path).

Guidelines:

• MUST place every new skill in exactly one tier using the portability question above, once Is the Material a Skill? has settled that it is one, and before writing its SKILL.md.
• MUST NOT store a repository-local skill under the source directory or manage it with npx skills; it never appears in skills-lock.json.
• MUST move a skill between tiers deliberately when its scope changes — a repository-local skill later generalized for sharing moves its source to skills/<name>/ and is reinstalled with the CLI — never by keeping a copy in both.
• MAY read a skill's tier off skills-lock.json: a skill listed there is distributable and installed; one absent from it is repository-local.

Repository-Local Skills

A repository-local skill's committed copy under the skill root is its source of truth. The prohibition on hand-editing installed copies does not apply here — editing these files in place is the correct workflow.

Guidelines:

• MUST edit a repository-local skill directly under the skill root (.claude/skills/<name>/, or the equivalent path the host reads) — its SKILL.md, references/, and any scripts/ — and commit those files; there is no separate source directory and no install step.
• MUST author it to the same standard as any other skill — frontmatter, naming, discovery metadata, progressive disclosure — per your project's skill-authoring conventions.
• MUST rename a repository-local skill with a git mv of its directory plus a matching frontmatter name update, and update every reference to the old name in the same change.

Distributable Skills: Install and Refresh

A distributable skill is authored under skills/<name>/SKILL.md (with its references/ beside it) and installed with the CLI. The CLI is run through npx; when the environment does not support symlinks, installs use --copy (the copy lands as a real directory under the skill root).

Commands:

• Install or refresh every managed skill:

  npx skills add ./skills --agent claude-code --skill '*' --yes --copy
  

• Refresh a single skill by name:

  npx skills add ./skills --agent claude-code --skill <name> --yes --copy
  

• Refresh several named skills — one --skill flag each:

  npx skills add ./skills --agent claude-code --skill <name> --skill <other-name> --yes --copy
  

• List installed skills: npx skills list

• Remove an installed skill: npx skills remove <name> (then delete its skills/<name>/ source, and update the host's written skill index where it keeps one).

Guidelines:

• MUST author a distributable skill under the source directory (skills/<name>/), never directly under the skill root.
• MUST NOT hand-edit an installed copy under the skill root when you own its source; edit the source and reinstall.
• MUST re-run the install after editing any source skill so the committed installed copy and skills-lock.json match the source.
• MUST commit every installed skill root — .claude/skills/<name>/, .agents/skills/<name>/, or both — and skills-lock.json alongside the skills/ source; they are tracked artifacts, not gitignored.
• MUST pass --copy when symlinks are unsupported; a symlink install leaves the skill root empty or broken there.
• MUST use --skill '*' to refresh all managed skills after a broad change, or --skill <name> for a targeted one; --skill takes exactly one skill per flag, so installing several means repeating it (--skill <name> --skill <other-name>), not passing a list.
• MUST read a No matching skills found response — the CLI answering with the source's available-skill list where an install summary belongs — as a run that installed nothing: no skill reaches the skill root and no lockfile is written. A comma-separated --skill a,b,c is the usual cause, since the CLI does not split the value and so matches no skill at all, and that available-skill list reads like ordinary help rather than a failure.
• SHOULD run npx skills add from the repository root so ./skills resolves and skills-lock.json is written there.
• SHOULD confirm the install summary lists every expected skill as copied before committing — the check that catches a run which matched nothing and installed nothing.
• SHOULD retry with an explicit version specifier (npx --yes skills@latest …) when npx skills aborts with could not determine executable to run; the plain form above stays canonical, and the specifier is a fallback for environments where npx cannot resolve the bare package name.

Discovery and Active Loading

See active-loading.md for:

• installation, source agreement, discovery, and active content as separate observations
• same-name precedence, stale sessions, and unavailable source evidence
• diagnosis before an authorized installation change

Guidelines:

• MUST read active-loading.md when verifying a skill installation or refresh, or diagnosing missing discovery or unexpected loaded content.

Proposing a Change to an Installed Skill

A distributable skill's installed copy under the skill root is a generated artifact: the next install or npx skills upgrade regenerates it from its source and silently discards anything you typed into it. How you change such a skill therefore depends on whether you own its source.

The change usually announces itself while you are using the skill rather than before it: you load the skill for some other task and find a rule that is wrong, out of date, or silent on the case in front of you. That finding is what this section acts on. The question it answers is not whether to act — a rule left uncorrected misleads the next reader as it misled you — but where the action lands, and the installed copy is never the answer.

Determine which case you are in from the skill's source in skills-lock.json:

• The source points inside a repository you control (a local path or your own repo) → you own the source (first-party); change it locally.
• The source points at an upstream repository or registry you do not control → the skill was installed from outside (third-party); route the change upstream.

Acting on What You Found

A finding about a skill arrives in the middle of other work, which is what makes it easy to lose: correcting it in place is forbidden, and the task at hand has its own momentum. Sort it by tier, route it, and carry on — the proposal travels alongside the work rather than displacing it.

Guidelines:

• MUST treat a rule you find wrong, outdated, or missing while applying an installed skill as a change to route, not an observation to discard; sort it by the ownership question above before acting on it.
• MUST, when you own the source, make the change locally: edit the source under skills/<name>/, reinstall with the CLI, and commit the regenerated installed copy and skills-lock.json (see Distributable Skills: Install and Refresh). Never hand-edit the installed copy.
• MUST continue the task that exposed the finding under the skill exactly as installed while a proposal is pending; routing a change never blocks that work, and never licenses acting as though the proposed rule were already in force.
• SHOULD raise what generalizes — a rule that is wrong, outdated, or missing for any user of the skill — and record what only suits your project as a local convention instead of an upstream request.
• SHOULD, when you need a local-only deviation you cannot wait on upstream for, fork the skill into your own distributable source deliberately — copy it under your skills/<name>/, repoint its skills-lock.json source, and manage it first-party from then on — rather than hiding the change as an edit to the installed copy. Record that you have diverged from upstream.
• SHOULD name any proposal you filed or left pending in the work's completion report, so the finding outlives the session that produced it.

Filing an Upstream Feature Request

The upstream repository is the source of truth for a third-party skill, so changing one means requesting the change there — a feature request or bug report describing the behavior the skill should have. Two facts shape how it is filed: the maintainer who reads it has no access to your project, and opening it is a public write on a repository you do not own.

Guidelines:

• MUST NOT hand-edit the installed copy of a skill installed from an upstream you do not own — a reinstall or npx skills upgrade overwrites it from upstream, so the edit is lost and, until then, masquerades as source.
• MUST propose a change to a skill installed from outside as a feature request or bug report on its upstream repository, resolving that upstream from the skill's source in skills-lock.json; search its issue tracker first and add to an existing request that already covers the finding rather than filing a duplicate.
• MUST obtain the human's go-ahead on the drafted title and body before opening the issue — it is a public write, under their identity, on a repository the project does not own; a standing instruction to file such findings as they arise is that go-ahead.
• MUST write the request so a maintainer with no access to your project can act on it: the skill and the section or rule at issue, the situation that exposed it, the current behavior and the behavior it should have, and why it generalizes beyond your project.
• MUST keep the upstream proposal to an issue; do not open a pull request on the upstream repository.
• MUST report the finding and the drafted request back to the human instead when the upstream does not resolve to a reachable issue tracker — never drop it, and never edit the installed copy in its place.
• MUST pull an accepted upstream change by re-running the install/upgrade against the upstream source, not by editing files under the skill root.

The Lockfile

skills-lock.json is the install lockfile — analogous to package-lock.json. It records each distributable skill's source, sourceType, and a computedHash of the installed content, and is committed so the installed state is reproducible and drift is detectable. Repository-local skills never appear in it.

Since skills@1.5.22, the CLI writes a local source as a path relative to the lockfile's own directory — /-separated, so it stays portable across checkouts and platforms — rather than as an absolute path. It falls back to an absolute one only where no relative path exists, as when the source sits on a different filesystem root. Refreshing any single skill rewrites every local entry's source through that same normalization, not only the one refreshed, so a lockfile diff that touches entries for skills you did not edit is this normalization sweep, not drift. A CLI older than 1.5.22 still writes the absolute form, so a checkout's lockfile can carry either form depending on which version last ran the install.

Verified against the v1.5.22 release notes, published 2026-08-05.

Guidelines:

• MUST commit skills-lock.json and regenerate it by running the install command, never by hand-editing.
• MUST treat a computedHash change with no corresponding source edit as install drift to investigate, not to blindly commit.
• SHOULD treat a diff touching only local source fields, with no computedHash change, as the normalization sweep above rather than drift; confirm which CLI version last ran the install when a lockfile keeps alternating between the two forms.

Installed-Copy Drift Check

The installed copies are tracked artifacts, not build output, so nothing stops a hand-edit to one — and the next install discards it silently. This skill bundles scripts/check-installed-copies.mjs, a dependency-light Node check (standard library only) that compares each source skill against its installed copy file by file and byte for byte, so a forgotten reinstall or a hand-edit fails before merge instead of surfacing later.

Example:

# Substitute the skill root the host reads (.claude/skills, .agents/skills, …).
node skills/agent-skill-management/scripts/check-installed-copies.mjs skills .claude/skills

Both roots are required, and there is no default: a directory layout is a project's own choice, and a guessed root that matches nothing reports no drift — a pass indistinguishable from a real one. It reports four kinds of difference (a file missing from the installed copy, a file present only there, differing content, and a source skill with no installed copy at all), plus an installed skill that has neither a source nor repository-local status. Mark each repository-local skill with a repeatable --local <name>, or the check reads it as drift. It deliberately ignores skills-lock.json: the lockfile is written only by an install, so it records what the last install did rather than what is on disk now, and cannot witness an edit made to an installed copy afterwards — precisely the drift this check exists to catch. Its source field also names where a skill came from rather than where its installed copy lives, so it identifies neither of the two roots the check compares. Directory contents are the truth.

It exits 0 when every installed copy matches, 1 on drift, and 2 on a bad invocation or a root that is not a directory.

Guidelines:

• MUST run this check after any change to a distributable skill, and treat exit 1 as a forgotten reinstall or a hand-edited copy rather than as a reason to edit the installed tree.
• MUST name both roots explicitly at every call site, including the project's own gate, since the check cannot infer a layout it was not told.
• MUST register every repository-local skill through --local (or the set inside a project's own copy) rather than letting a sourceless installed skill pass, or a DELETED source becomes indistinguishable from a deliberate one.
• SHOULD wire it into the project's merge gate: it is offline and deterministic, which is exactly what a gate needs.

Verification

Skill changes are documentation changes: they gate on format, lint, and relative-link integrity, plus a skill structure validator where the project ships one.

Guidelines:

• MUST run the project's documentation checks (format, lint, relative-link integrity) after any skill change — a direct edit or a reinstall — and fix any failure before committing.
• MUST run the relative-link check whenever a skill's files or links moved, since a stale link inside an installed copy fails the same check as the source.
• MUST confirm, after adding, renaming, moving, or removing a skill or a reference file, that discovery metadata and parent routing still resolve to the change — per your skill-authoring conventions, which own those rules — because a tier move changes paths that discovery and routing depend on.
• SHOULD validate a changed skill with the structure validator your skill-authoring conventions ship, if any.
• SHOULD diff a reinstalled copy against its source (git diff --stat) to confirm the reinstall changed exactly the expected files.