fp-check

fp-check is a skill for Claude Code from ByamB4/find-cve-agent. It costs 37 tokens per session (1,301 once invoked), scanned A, original, Apache-2.0.

A final security-review checklist for rejecting false positives, meaning reported bugs that are not actually exploitable or do not affect the claimed code path.

In plain words
What is it for?
Use it before submitting any vulnerability report or CVE claim; it is not intended for ordinary bug hunting, style review, or feature work.
Why use it?
It forces the reviewer to trace the real data flow, challenge the finding, and document the exact cause and impact before submission.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the find-cve-agent plugin — 21 skills, 7 commands, 5 agents shipped together

Good fit Use it before submitting any vulnerability report or CVE claim; it is not intended for ordinary bug hunting, style review, or feature work.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/byamb4/find-cve-agent/fp-check
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add ByamB4/find-cve-agent --skill fp-check
Clone the repo
git clone --depth 1 https://github.com/ByamB4/find-cve-agent

Made for: Claude Code.

Or install find-cve-agent, the plugin that ships this one along with the rest of its 21 skills, 7 commands, 5 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fp-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/byamb4/find-cve-agent/fp-check/github.svg)](https://agentmods.dev/skills/byamb4/find-cve-agent/fp-check)
Your own site
<a href="https://agentmods.dev/skills/byamb4/find-cve-agent/fp-check"><img src="https://agentmods.dev/badge/skills/byamb4/find-cve-agent/fp-check/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fp-check

Your own site · 80×15
<a href="https://agentmods.dev/skills/byamb4/find-cve-agent/fp-check"><img src="https://agentmods.dev/badge/skills/byamb4/find-cve-agent/fp-check.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,301 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.01301
Opus 5 $0.00018 $0.00651
Sonnet 5 $0.00007 $0.00260
Haiku 4.5 $0.00004 $0.00130

Measured 10d ago against content hash 05bf90872ad7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fp-check scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/fp-check/SKILL.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.

False Positive Check — MANDATORY Pre-Submission Verification

When to Use

Before ANY finding is submitted. No exceptions. This is the final gate.

When NOT to Use

  • Finding or hunting for bugs (use Hunter workflow instead)
  • General code review for style/performance
  • Feature development or non-security tasks

Rationalizations to Reject

Rationalization Why It Is Wrong Action
"This pattern looks dangerous" Pattern recognition is not analysis Trace actual data flow
"Similar code was vulnerable elsewhere" Each context differs Verify this specific instance
"This is clearly critical" LLMs are biased toward seeing bugs Complete devil's advocate
"Skipping verification for efficiency" No partial analysis allowed Run all gates

Step 0: Restate the Claim

Restate the vulnerability in one precise sentence. If you cannot, it's likely false.

  • What: exact vulnerability type and root cause
  • Where: file:line of the sink
  • How: data flow from attacker input to sink
  • Impact: concrete security consequence
  • Who: attacker privilege level required
  • Bug class: consult references/bug-class-verification.md

Half of false positives collapse at this step — the claim doesn't make coherent sense.

Route: Standard vs Deep

Standard — clear claim, single component, well-understood bug class, no concurrency. Deep — ambiguous claim, cross-component flow, race conditions, logic bugs, or standard was inconclusive.

Start with Standard. It has built-in escalation checkpoints.

6-Gate Review — ALL Must Pass

Gate 1: Process Completeness

  • Source identified (where attacker input enters)
  • Sink identified (where dangerous operation occurs)
  • Complete data flow traced source to sink
  • All transformations/validations documented

Gate 2: Reachability

  • Attacker can reach the vulnerable endpoint
  • Attacker controls the data that reaches the sink
  • No auth barrier blocks access (or bypass is part of finding)
  • Input is not sanitized before reaching sink

Read the full file on GitHub · 141 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 141 lines · 37 tokens per session scan A 05bf90872ad7

Subscribe to this mod's changes

fp-check is a skill published in the GitHub repository ByamB4/find-cve-agent (48 stars, last pushed 5mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 1,301 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

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