Custom Agent Skills by Lines. Harness-agnostic — skills in this repo work across Claude Code, Pi, Cursor, Copilot, Gemini CLI, and any other client that follows the Agent Skills open standard.
Two design goals drive every skill here:
- Single source, any harness. No tool-specific names or platform assumptions. The same skill file runs wherever the standard is supported.
- Resilient across model sizes. Skills are hardened for smaller-parameter models that may struggle with instruction following — explicit one-at-a-time question formats, prescriptive decision forks, no vague "handle this appropriately" language.
| Skill | Description |
|---|---|
| opencraft-skill | Meta skill for creating Agent Skills. Three modes: Extract (capture from conversation history), Design (build from scratch), Refine (improve an existing skill). Includes a bundled eval and description-optimization pipeline. |
Agent Skills are plain Markdown files (SKILL.md) that give AI agents reusable, specialized behavior. A skill lives in a named directory and is loaded by the agent when a task matches its description.
skill-name/
├── SKILL.md # Required: metadata + instructions
├── agents/ # Optional: subagent instruction files
├── scripts/ # Optional: executable helpers
├── references/ # Optional: reference docs loaded on demand
└── assets/ # Optional: templates, resources
The format is an open standard. Full spec and guides are in docs/guides/.
- Copy the skill directory (e.g.
opencraft-skill/) into your agent's skills directory.- Claude Code / Pi / most harnesses:
~/.agents/skills/ - Check your harness docs for the exact path.
- Claude Code / Pi / most harnesses:
- Start a session. The skill activates automatically when a task matches its description.
Skills in this repo may include two tiers of tooling:
Tier 1 — stdlib Python 3, runs anywhere:
scripts/quick_validate.py— spec-check a skill before shipping itscripts/aggregate_benchmark.py— aggregate eval results into a benchmark reportscripts/package_skill.py— zip a skill into a distributable.skillfile
Tier 2 — LLM provider required:
scripts/run_eval.py— automated trigger-rate measurement (Claude Code CLI only)scripts/improve_description.py— LLM-driven description rewriting (any provider)scripts/run_loop.py— full 60/40 train/test optimization loop (any provider)
Provider detection for improve_description.py: ANTHROPIC_API_KEY → OPENAI_API_KEY → claude -p fallback.
run_eval.py and run_loop.py (eval step) require Claude Code CLI — trigger testing is harness-specific.
docs/guides/agentskills-guide.md— full guide (overview, spec, quickstart, best practices, evals, description optimization, scripts, client implementation)- agentskills.io — upstream standard
MIT