"Slint" matching MCP connectors:

Lint a SKILL.md for frontmatter, structure, secrets and size. All 6 tools free.

Checks CLAUDE.md, AGENTS.md or a system prompt for 12 safeguards unattended agents need.

ESLint rules key count, body discarded

A fully free linter for agent skill files: lint_skill validates YAML frontmatter, structure, size budgets, and safety phrasing with a pass/fail verdict; packaging_check validates zip layout against marketplace rules; plus regex_test, json_validate, diff_texts, and cron_explain for skill authors. No license or account required.