mcaf-security-baseline

A baseline guide for engineering security around secrets, authentication, permissions, data flows, external inputs, and secure defaults. It is intended for changes with security impact that do not need a full application-security review.

In plain words
What is it for?
Reviewing changes that touch authentication, authorization, secrets, external integrations, storage, transport, or CI and deployment permissions.
Why use it?
It gives developers a practical checklist before they change a security-sensitive path. This helps expose unsafe trust boundaries, permissions, data handling, or pipeline settings early.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/managedcode/mcpgateway/mcaf-security-baseline
Any agent
npx skills add managedcode/MCPGateway --skill mcaf-security-baseline
Clone the repo
git clone --depth 1 https://github.com/managedcode/MCPGateway

Made for: Claude Code, Codex.

Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 826 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 97% copy Near-identical to another mod 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 $0.00055 $0.00826
Opus 5 $0.00028 $0.00413
Sonnet 5 $0.00011 $0.00165
Haiku 4.5 $0.00006 $0.00083

Measured yesterday against content hash 1fe51a864a12, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mcaf-security-baseline 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 yesterday.

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.

Origin

This is a copy

97% identical to mcaf-security-baseline — 21 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.codex/skills/mcaf-security-baseline/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCAF: Security Baseline

Trigger On

  • a change has security impact but does not need a full separate AppSec exercise
  • the work touches auth, secrets, trust boundaries, data flow, or pipeline permissions
  • the team needs secure-default guidance before implementing

Value

  • produce a concrete project delta: code, docs, config, tests, CI, or review artifact
  • reduce ambiguity through explicit planning, verification, and final validation skills
  • leave reusable project context so future tasks are faster and safer

Do Not Use For

  • a full standalone threat-modeling engagement
  • generic code review with no security surface

Inputs

  • the changed boundary, data flow, or integration
  • auth, secret, and permission model for the affected path
  • current security docs, ADRs, or CI rules

Quick Start

  1. Read the nearest AGENTS.md and confirm scope and constraints.
  2. Run this skill's Workflow through the Ralph Loop until outcomes are acceptable.
  3. Return the Required Result Format with concrete artifacts and verification evidence.

Workflow

  1. Identify the security surface:
    • authn and authz
    • secrets
    • external inputs
    • storage and transport
    • pipeline permissions
  2. Apply secure defaults and least privilege before adding behaviour.
  3. If the change introduces a trust boundary, update or add an ADR and link the reasoning.
  4. Pull the relevant security references, not the whole set.

Deliver

  • security-aware design or implementation guidance
  • updated security checkpoints in docs, ADRs, or CI
  • the right threat-model references for the impacted area

Validate

  • secrets are handled explicitly
  • authn and authz assumptions are visible
  • new trust boundaries are documented
  • the change does not smuggle insecure defaults into the repo

Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

  1. Plan first (mandatory):
    • analyze current state
    • define target outcome, constraints, and risks
    • write a detailed execution plan
    • list final validation skills to run at the end, with order and reason
  2. Execute one planned step and produce a concrete delta.
  3. Review the result and capture findings with actionable next fixes.
  4. Apply fixes in small batches and rerun the relevant checks or review steps.
  5. Update the plan after each iteration.
  6. Repeat until outcomes are acceptable or only explicit exceptions remain.
  7. If a dependency is missing, bootstrap it or return status: not_applicable with explicit reason and fallback path.

Read the full file on GitHub · 100 lines

Files

What ships with it

3 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. yesterday First seen · 100 lines · 55 tokens per session scan A 1fe51a864a12

Subscribe to this mod's changes

mcaf-security-baseline is a skill published in the GitHub repository managedcode/MCPGateway (5 stars, last pushed 2d ago), licensed MIT. It adds 55 tokens to every session and 826 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to mcaf-security-baseline, differing in 21 lines, and is treated as a copy.