Borrowing it
Nothing to install: this file belongs to P4ST4S/mcp-audit. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/P4ST4S/mcp-audit/main/.agents/skills/variant-analysis/SKILL.mdgit clone --depth 1 https://github.com/P4ST4S/mcp-auditWrote 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.
[](https://agentmods.dev/skills/p4st4s/mcp-audit/variant-analysis)<a href="https://agentmods.dev/skills/p4st4s/mcp-audit/variant-analysis"><img src="https://agentmods.dev/badge/skills/p4st4s/mcp-audit/variant-analysis/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.
<a href="https://agentmods.dev/skills/p4st4s/mcp-audit/variant-analysis"><img src="https://agentmods.dev/badge/skills/p4st4s/mcp-audit/variant-analysis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00121 | $0.00846 |
| Opus 5.5 | $0.00048 | $0.00338 |
| Sonnet 5.5 | $0.00024 | $0.00169 |
| Haiku 4.5 | $0.00012 | $0.00085 |
Grade A, and why
variant-analysis 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Variant Analysis
Find the other instances of a bug you have already found. One root cause usually has several manifestations, and they are rarely in the module where you found the first one.
When to Use
- A vulnerability has been found and you need to search for similar instances
- Building or refining CodeQL/Semgrep queries for security patterns
- Performing systematic code audits after an initial issue discovery
- Analyzing how a single root cause manifests in different code paths
When NOT to Use
- Initial vulnerability discovery — use audit-context-building or a domain-specific audit
- General code review with no known pattern to search for
- Writing fix recommendations — use issue-writer
- Understanding unfamiliar code — use audit-context-building first
The Five Steps
Read the reference for a step when you reach it.
1. Understand the original issue. Extract the root cause — why the code is wrong, not what it does — and enumerate the directions a variant could hide in: related identifiers, other manifestations of the same mistake, data-type edge cases. → references/root-cause.md
2. Create an exact match. Write a pattern matching ONLY the known instance and confirm it hits. A pattern that matches nothing means you have misunderstood the bug, and every search built on it is calibrated against the wrong code.
3–4. Generalize one element at a time. Climb from the exact match toward the pattern family, running and reading all matches after each single change. Stop when more than half the matches are noise. → references/searching.md — abstraction ladder, tool selection, false-positive filters
5. Triage. Decide which candidates are real, and say so with a severity attached. → references/triage.md
Then write it up, including the patterns that failed and a CI rule to prevent regression. → references/reporting.md
Running it as a Workflow
What ships with it
17 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.
- agents/openai.yaml 247 B
- assets/trail-of-bits-mark.svg 3.0 KB
- references/reporting.md 1.5 KB
- references/root-cause.md 4.1 KB
- references/searching.md 4.5 KB
- references/triage.md 3.5 KB
- resources/codeql/cpp.ql 3.4 KB
- resources/codeql/go.ql 2.0 KB
- resources/codeql/java.ql 2.3 KB
- resources/codeql/javascript.ql 1.7 KB
- resources/codeql/python.ql 2.4 KB
- resources/semgrep/cpp.yaml 2.7 KB
- resources/semgrep/go.yaml 1.8 KB
- resources/semgrep/java.yaml 2.0 KB
- resources/semgrep/javascript.yaml 1.7 KB
- resources/semgrep/python.yaml 2.0 KB
- resources/variant-report-template.md 1.3 KB
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.
- 9d ago First seen · 77 lines · 121 tokens per session scan A 7b6b78e499bc
variant-analysis is a skill published in the GitHub repository P4ST4S/mcp-audit (8 stars, last pushed 9d ago), licensed Apache-2.0. It adds 121 tokens to every session and 846 once invoked, about $0.0005 per session on Opus 5.5. 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 2026-10-18.
Other skills, from other repositories
bmad-quick-dev
Implements any user intent, requirement, story, bug fix or change request by producing clean working code artifacts that follow the project's existing architecture, patterns and conventions. Use when the user wants to build, fix, tweak, refactor, add or modify any code, component or feature.
oh-my-posh
Install, configure, or troubleshoot Oh My Posh/ohmyposh: shell init, themes, segments, Nerd Font icons, and prompt setup on PowerShell, zsh, bash, or fish.
network-rca
Kubernetes network root cause analysis skill powered by Kubeshark MCP. Use this skill whenever the user wants to investigate past incidents, perform retrospective traffic analysis, take or manage traffic snapshots, extract PCAPs, dissect L7 API calls from historical captures, compare traffic patterns over time, detect…
pinchtab-dev
Develop and contribute to the PinchTab project. Use when working on PinchTab source code, adding features, fixing bugs, running tests, or preparing PRs. Triggers on "work on pinchtab", "pinchtab development", "contribute to pinchtab", "fix pinchtab bug", "add pinchtab feature".
printing-press-amend
Amend a published CLI from one of two input sources: (1) dogfood mode mines the active Claude Code session transcript for friction (missing flags, hand- rolled API payloads, silent-null returns); (2) direct-input mode accepts user-supplied asks (rename a command, add commands or feeds, fix a named bug, optionally…
printing-press-output-review
Internal sub-skill: agentic review of a printed CLI's sampled command output for plausibility issues that rule-based checks can't encode (substring-match relevance, format bugs, silent source drops, ranking failures). Invoked via the Skill tool by the main printing-press skill at Phase 4.85 and printing-press-polish…