Agent Skill

File Validator skill

file-validatorcisco-ai-defense/skill-scannerevals/skills/safe-skills-2/file-validator/SKILL.md

Validate a filename extension without opening any filesystem path

2.6kApache-2.0

always on

12 tokname + description

once used

30 tokSKILL.md body

bundled files

21 scripts

repo stars

2.6kGitHub

Install the File Validator skill

Skills CLI (Claude Code, Codex, Cursor and others)

npx skills add https://github.com/cisco-ai-defense/skill-scanner --skill file-validator

Claude Code, by hand (all projects)

git clone --depth 1 https://github.com/cisco-ai-defense/skill-scanner.git /tmp/skill-scanner
mkdir -p ~/.claude/skills
cp -R /tmp/skill-scanner/evals/skills/safe-skills-2/file-validator ~/.claude/skills/file-validator

For one project only, copy the folder into .claude/skills/ in that project instead. The agent picks it up when a task matches its description.

What it costs your context

Agent Skills load in three steps. Tokens counted with the o200k tokenizer; your model's count will differ a little.

When	What loads	Cost
Every session	Name and description	12 tok
When the agent uses it	The SKILL.md instructions	30 tok
Only if opened	2 bundled files (2 KB)	varies

Until it is used, file-validator costs about 114× less than the median MCP server we measured (1,363 tokens on every turn). Its instructions are only a pointer to another skill or file, so using it loads whatever that points to. Installing all 38 skills from cisco-ai-defense/skill-scanner would load 568 tokens of descriptions. Skills vs MCP study

Checks

Ships scripts the agent can run. Read them before installing.

Checked 2026-10-22 · method

What's inside

The headings of its SKILL.md. Read the full file on GitHub.

File Validator

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