Add Skill

add-skill

Builds one production-quality skill in skills//, eval-first. Read docs/skill-authoring.md and docs/evals.md once per session before starting; they are the rulebook this workflow enforces. If invoked as /add-skill , treat $ARGUMENTS as the skill name or idea to scope in step 1.

When NOT to use

• Creating a new skills repository → that happens in the workspace above this repo.
• Infrastructure work (hooks, CI, validator, docs) → plain editing, PR-level scrutiny.
• A "skill" that merely restates what the model already does well → don't build it;

a skill must fix a specific observed failure.

Workflow

1. Scope. State in one sentence what the skill does and the concrete failure it

fixes. If the sentence needs "and", split into multiple skills and do them one at a time. Check skills/ and the README catalog for overlap — near-neighbor descriptions steal each other's triggers; adjust scope or plan disjoint wording.

1. Gather. Read .local/ recursively — every subfolder and file is source

material (research, examples, constraints). Then research beyond it: web-search the topic for current facts, official docs, and prior art; verify anything load-bearing against primary sources, and cross-validate contested or high-stakes facts (external APIs, schemas, security claims) with /cross when available. Verified facts a skill depends on go into skills//references/ as cleaned, tracked files — never cite .local/ paths from a skill.

1. Evals first. Create skills//evals/evals.json per docs/evals.md:

≥8 should_trigger (vary formality, typos, terseness), ≥8 should_not_trigger (near-misses sharing keywords), 3–5 quality cases with plain-language expected_behavior assertions. If you can't write these, the scope is unclear — go back to step 1.

1. Draft SKILL.md. Frontmatter: name == folder name; description on a

single line, third person, [what] + [use when …] + [not for …], 150–400 chars, trigger keywords in the first ~120. Body per the structure in docs/skill-authoring.md: purpose → when/when-not → numbered workflow → output spec → gotchas → pointers. Under 500 lines; deterministic steps as scripts/ (non-zero exit on failure); long material as references/ with a TOC.

1. Validate. make check must exit 0. The write-time hook already validated the

file; fix every error and triage every warning it printed.

1. Trigger self-test. For at least 3 should-trigger and 2 should-not-trigger

prompts, reason explicitly: would the description alone (not the body) route this prompt here, against every other skill in the catalog? Fix the description, not the evals. Recommend the user run 2–3 fresh-session probes for the riskiest cases.

1. Register. Add/update the skill's row in the README catalog table, add a

CHANGELOG.md entry, and put the skill in exactly one skills.sh.json grouping (engaging one-sentence group descriptions — that file is the repo's skills.sh listing copy). Re-check descriptions of sibling skills for new overlap. Do not commit or push — leave all changes for the owner to review.

Output spec (Definition of Done)

• skills// with SKILL.md + evals/evals.json (+ scripts/references as needed)
• make check → 0 errors; README catalog + CHANGELOG updated
• A 3-line summary: purpose, trigger phrase examples, known limitations

Gotchas

• Keep description on ONE physical line — multi-line values have failed to load

in some runtimes and the validator blocks them; never work around the validator.

• Don't paste failed eval prompts verbatim into the description (overfitting);

generalize the missing verb/noun instead.

• Over-triggering fix = add targeted "Not for …" noun phrases from the actual

false-positive overlap; don't delete positive triggers.

• Model upgrades shift routing — note in your summary that evals should be re-run

after the next model release.

Source & license

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

• Author: Paldom
• Source: Paldom/skillskit
• License: MIT

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