Show HN: SkillPreflight – score AI agent skills before installing them

SkillPreflight, a new open-source command-line tool, scores AI agent skills on a 100-point scale across security, permission restraint, token efficiency, lightweight footprint, maintainability, reliability, and compatibility before installation. The tool, run via npx, scans local directories or GitHub repositories for skills used in Codex, Claude Code, Cursor, and Gemini CLI, and supports JSON policy files to exclude files and ignore rules. It aims to help users avoid unsafe or bloated third-party skills by providing pre-install safety checks.

SkillPreflight is a pre-install safety, token, and maintainability scorecard for AI agent skills. It helps users decide whether a Codex, Claude Code, Cursor, Gemini CLI, or other agent skill is safe and lightweight enough to install. If SkillPreflight helps you vet a third-party skill, consider starring the repository so more users can discover safer pre-install checks. Run without installing: npx skill-preflight scan ./my-skill Scan a GitHub repository before installing it: npx skill-preflight scan https://github.com/user/some-skill Scan one skill inside a large repository by pasting its GitHub directory or SKILL.md URL: npx skill-preflight scan https://github.com/user/skills/tree/main/skills/my-skill npx skill-preflight scan https://github.com/user/skills/blob/main/skills/my-skill/SKILL.md Scan common local skill directories: npx skill-preflight scan --installed For repositories containing many skills, show a compact list of the 20 lowest-scoring skills: npx skill-preflight scan https://github.com/user/skill-collection --summary --top 20 Apply a local policy when scanning a repository: npx skill-preflight scan . --config skill-preflight.json npm install npm run build npm test npm run dev -- scan examples/risky-skill SkillPreflight uses a 100-point score: | Category | Points | What it checks | |---|---|---| | Security | 35 | Dangerous commands, secret access, exfiltration, prompt injection, remote script execution | | Permission restraint | 15 | Over-broad activation, unnecessary shell/network/file access | | Token efficiency | 15 | Oversized SKILL.md , repeated content, poor progressive disclosure | | Lightweight footprint | 10 | File count, total size, dependencies, large assets | | Maintainability | 10 | README, license, frontmatter, examples, documentation hygiene | | Reliability | 10 | Tests, fixtures, deterministic workflow, error handling | | Compatibility | 5 | Hardcoded local paths, OS-specific assumptions, fragile shell usage | Repeated locations for the same rule remain visible, but each rule ID deducts points only once per skill. This keeps large repositories from receiving a lower score merely because the same issue appears in several files. When one skill directory contains other skills, SkillPreflight reports each SKILL.md as a separate skill and excludes child-skill files from the parent score. skill-preflight scan <target Options: --installed Scan common installed skill directories. --format <format text, json, markdown, html, or sarif. Default: text. --out <file Write report to a file. --fail-below <score Exit with code 1 if any scanned skill is below this score. --fail-on <severity Exit for findings at or above info, low, medium, high, or critical. --config <file Load an explicit JSON policy file. --exclude <glob Exclude a target-relative path glob. Repeat as needed. --ignore-rule <id Suppress a rule ID or wildcard pattern. Repeat as needed. --keep-temp Keep temporary clones for debugging. --summary Show aggregate results and the lowest-scoring skills only. --top <count Number of skills shown with --summary. Default: 20. Summary mode supports text, JSON, Markdown, and HTML output. SARIF always contains the full set of findings for code scanning. Use an explicit JSON policy to keep generated files and reviewed false positives out of a scan: { "exclude": "fixtures/ ", "vendor/ " , "ignoreRules": "compatibility.os-specific-command" , "failBelow": 70, "failOn": "high" } skill-preflight scan . --config skill-preflight.json Config files are never loaded from a scanned repository automatically. This prevents an untrusted remote skill from suppressing its own findings. CLI exclusions and ignored rules are merged with the config; CLI score and severity gates take precedence. Suppressed findings remain counted in the report so policy decisions are visible. See docs/policy.md for glob behavior and CI examples. Generate Shields-compatible badge JSON: skill-preflight badge ./my-skill --out skill-preflight-badge.json The badge payload can be served through a static endpoint or GitHub Pages: { "schemaVersion": 1, "label": "SkillPreflight", "message": "91/100 A", "color": "brightgreen" } After the package is published to npm and the repository is tagged, skill authors can scan every PR: name: SkillPreflight on: pull request, push jobs: scan: runs-on: ubuntu-latest steps: - uses: actions/checkout@v6 - uses: agent-contracts/skill-preflight@v1 with: target: "." config: skill-preflight.json Without a config, the Action fails below 70 by default. A policy file's failBelow value is used when config is provided; an explicit fail-below input overrides both. For GitHub code scanning, emit SARIF: skill-preflight scan . --format sarif --out skill-preflight.sarif See docs/github-action.md for the full workflow. In August 2026, SkillPreflight scanned a frozen, commit-pinned sample of 40 public agent skills. The sample averaged 80.8/100 , with a median score of 85.5/100 . Read the reproducible benchmark report /agent-contracts/skill-preflight/blob/main/benchmarks/2026-08-public-skills/README.md for the methodology, aggregate findings, source snapshot, and raw JSON/CSV data. This convenience sample is not an ecosystem ranking, and static findings require manual review. SkillPreflight does not execute scripts inside scanned skills. It only reads files and performs static analysis. Oversized files are measured without being loaded into text analysis. shell-super-agent: 35/100 F - High risk, do not install blindly Top findings: - CRITICAL Remote script execution pattern SKILL.md:15 - HIGH Prompt injection language SKILL.md:8 - HIGH Potential secret or credential access SKILL.md:10 See docs/rules.md for the current static analysis rule catalog, including dependency, install-script, MCP config, token, and compatibility checks. See docs/release.md for the first npm and GitHub release checklist.