Askl

askl

askl is a standalone command-line linter for the Agent Skills specification. It scans every SKILL.md under a repository's skill roots, validates frontmatter and referenced Markdown files, and reports issues with exact file and line positions.

Running it

askl                       # lint the default skill roots
askl --format json         # machine-readable output
askl --list-rules          # show every registered rule

Default skill roots (relative to the current working directory): .agent/skills, .agents/skills, .claude/skills, agents/skills, skills.

Exit codes: 0 clean, 1 a rule reported an error (or a warning with --deny-warnings), 2 a usage or config problem (bad --rule value, invalid config file).

Fixing a reported issue

1. Read the diagnostic: : error ().
2. Open ` at and address ` directly — every rule

message states exactly what must change.

1. Re-run askl to confirm the fix and check for any remaining issues.

Common fixes:

• valid-frontmatter: add the missing name/description field, fix the

YAML, or shorten a field past its length limit.

• name-matches-directory: rename the skill's name field or its

directory so they match.

• no-broken-local-references / no-deep-references: fix the Markdown

link target, or move the referenced file to at most one directory below SKILL.md.

• no-empty-skill-body: add instructions after the closing ---.
• skill-index-budget: shorten name/description across the flagged

skills, since the message reports a combined total, not one file's size.

Suppressing a specific diagnostic

Only suppress a diagnostic when the rule's rationale genuinely does not apply to that line — never to silence an unaddressed real issue. Add an HTML comment to the SKILL.md source:

See [the Windows helper](scripts\help.ps1).

` suppresses for the line that follows the comment; ` suppresses it for the whole file regardless of where the comment sits. Both accept a space-or-comma-separated list of rule names, and omitting the list suppresses every rule.

Configuring rules

askl reads the nearest .asklrc.jsonc (or .asklrc.json), searching from the current directory upward:

{
	"roots": [".agents/skills"],
	"rules": {
		"no-unknown-frontmatter-fields": "error",
		"skill-index-budget": ["warn", { "maxCharacters": 8000 }],
	},
}

--roots and --rule = on the command line override the config file for a single invocation.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: ryoppippi
• Source: ryoppippi/askl
• License: MIT
• Homepage: https://www.npmjs.com/package/oxlint-plugin-agent-skills

Install and usage instructions live in the source repository linked above.