skill-prescan#

Pre-scan your SKILL.md locally before publishing to ClawHub. This tool simulates the ClawScan security review using the same system prompt and evaluation criteria as the real ClawHub scanner, allowing you to iterate on your skill documentation until it passes.

When to Use#

• Before publishing a new skill to ClawHub
• After modifying a skill that previously failed the security review
• To understand why ClawHub flagged your skill as "suspicious"
• To iterate locally without consuming publish attempts

Requirements#

• Python 3.8+
• An OpenAI API key (or any OpenAI-compatible API)

Usage#

bash

# Basic scan (uses OPENAI_API_KEY env var)
python3 {baseDir}/scripts/scan.py path/to/SKILL.md

# Specify API key and model
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --api-key sk-xxx --model gpt-5.5

# Use a custom OpenAI-compatible endpoint
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --base-url https://your-gateway.com --model gpt-5.5

# Use Anthropic Claude
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --provider anthropic --api-key sk-ant-xxx

# Run multiple times to check consistency
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --runs 3

# Output raw JSON
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --json

# Skip the data-transmission confirmation prompt (for scripts/CI)
python3 {baseDir}/scripts/scan.py path/to/SKILL.md --yes

Data Transmission & Privacy#

This tool reads the target SKILL.md and sends its full contents to the remote LLM endpoint you configure ( --base-url / OPENAI_BASE_URL, default https://api.openai.com). That endpoint is a third party that may log, cache, or retain the transmitted text.

• Before sending, the tool prints a notice and asks for confirmation.
• In a non-interactive session it refuses to send unless you pass --yes.
• Only SKILL.md is transmitted. Other files in the skill directory (scripts, etc.) are listed in the payload manifest but their contents are not sent or analyzed locally — review them separately.
• Do not scan secrets or proprietary material you are unwilling to disclose to the configured endpoint.

Model Selection#

The real ClawHub scanner uses gpt-5.5 with reasoning.effort: "xhigh" and max_output_tokens: 16000. For the most accurate local simulation, use gpt-5.5 via any OpenAI-compatible endpoint (default).

ProviderFlagModelsAccuracy vs ClawHubOpenAI-compatible--provider openai (default)gpt-5.5, gpt-5, gpt-5.1Closest to real resultsAnthropic--provider anthropicclaude-sonnet-4-6, claude-opus-4-6More lenient

Note: the real scanner uses the Responses API with extended reasoning, which is not available through Chat Completions. Local results may be slightly more lenient than production.

Understanding Results#

Verdicts#

• benign — Your skill should pass ClawHub's review and be searchable.
• suspicious — Your skill will be flagged for Review. Review the concerns and user guidance.
• malicious — Your skill will be blocked entirely.

Dimensions (new format)#

The scanner evaluates 5 dimensions, each rated ok, note, or concern:

• purpose_capability — Is the stated purpose coherent with actual capabilities?
• instruction_scope — Are the instructions bounded and user-controlled?
• install_mechanism — Is the install path transparent and verifiable?
• environment_proportionality — Are credentials/environment requirements proportionate?
• persistence_privilege — Does the skill persist or escalate privileges?

Key Rule from ClawHub's Scanner#

"A coherent skill with only purpose-aligned notes should remain benign with clear user guidance." "Shell commands, network calls, file I/O, credentials, or install steps are not malicious by themselves; classify based on purpose fit, scope, provenance, and artifact evidence."

Writing Effective Safety Documentation#

1. Disclose all capabilities explicitly — the scanner flags hidden or undisclosed behavior.
2. Bound high-impact actions — document user approval mechanisms, scope limits, reversibility, and containment.
3. State structural limitations — explicitly list what the tool cannot do.
4. Use neutral framing — describe behaviors factually rather than defensively.
5. Be specific about data flows — describe what is transmitted, to where, and what boundaries apply.

Environment Variables#

VariableDescriptionDefaultOPENAI_API_KEYAPI key for the LLM service(required)OPENAI_BASE_URLBase URL for OpenAI-compatible APIhttps://api.openai.com``SCAN_MODELModel to use for scanninggpt-5.5``SCAN_PROVIDERProvider: openai or anthropic``openai

How It Works#

The scanner sends your SKILL.md content to an LLM with the exact same system prompt that ClawHub's ClawScan uses (extracted from the open-source ClawHub repository). The LLM evaluates your skill across multiple security dimensions and returns a verdict.

Limitations#

• Local scan uses Chat Completions API; ClawHub uses Responses API with reasoning.effort: "xhigh" which may produce stricter results.
• ClawHub also runs a VirusTotal scan separately — this tool only simulates the LLM (ClawScan) portion.
• Results may vary between runs due to LLM temperature (default 1.0 on the real scanner).
• The scanner prompt may be updated by ClawHub at any time — check the source repo for the latest version.