security-headers

security-headers is a skill for Claude Code, Codex from fusengine/agents. It costs 42 tokens per session (465 once invoked), scanned A, original, MIT.

An audit and configuration tool for HTTP security headers, which tell browsers how a web application should handle content, connections, framing, and browser features.

In plain words
What is it for?
Use it to inspect and generate framework-specific settings for Next.js, Laravel, Express, or Django applications, then validate the resulting headers.
Why use it?
It finds missing or weak protections such as Content Security Policy, HTTPS enforcement, and clickjacking defenses.

Skill for Claude CodeCodex

Part of the fuse-security plugin — 5 skills, 1 command, 1 agent shipped together

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/fusengine/agents/security-headers
Any agent
npx skills add fusengine/agents --skill security-headers
Clone the repo
git clone --depth 1 https://github.com/fusengine/agents

Made for: Claude Code, Codex.

Or install fuse-security, the plugin that ships this one along with the rest of its 5 skills, 1 command, 1 agent.

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 security-headers

README.md
[![agentmods](https://agentmods.dev/badge/skills/fusengine/agents/security-headers.svg)](https://agentmods.dev/skills/fusengine/agents/security-headers)
Your own site
<a href="https://agentmods.dev/skills/fusengine/agents/security-headers"><img src="https://agentmods.dev/badge/skills/fusengine/agents/security-headers.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 465 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00042 $0.00465
Opus 5 $0.00021 $0.00233
Sonnet 5 $0.00008 $0.00093
Haiku 4.5 $0.00004 $0.00047

Measured yesterday against content hash 114016d1265d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security-headers 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.

plugins/security-expert/skills/security-headers/SKILL.md · 59 lines

What it actually says

It detects the framework (Next.js next.config.js headers/middleware.ts, Laravel SecurityHeaders middleware, Express helmet, Django SECURE_* settings), checks the current configuration against best practice, generates a framework-specific fix, and validates the headers are properly set.

Security Headers Skill

Overview

Audit and configure HTTP security headers for web applications.

Required Headers

Header Purpose Severity if Missing
Content-Security-Policy Prevent XSS/injection HIGH
Strict-Transport-Security Force HTTPS HIGH
X-Content-Type-Options Prevent MIME sniffing MEDIUM
X-Frame-Options Prevent clickjacking MEDIUM
Referrer-Policy Control referrer info LOW
Permissions-Policy Control browser features LOW
X-XSS-Protection Legacy XSS filter LOW

Workflow

  1. Detect framework (Next.js, Laravel, Express, etc.)
  2. Check current header configuration
  3. Compare against security best practices
  4. Generate framework-specific configuration
  5. Validate headers are properly set

Detection Points

Framework Config Location
Next.js next.config.js headers, middleware.ts
Laravel SecurityHeaders middleware
Express helmet middleware
Django SECURE_* settings

References

Files

What ships with it

2 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 · 59 lines · 42 tokens per session scan A 114016d1265d

Subscribe to this mod's changes

security-headers is a skill published in the GitHub repository fusengine/agents (25 stars, last pushed 1mo ago), licensed MIT. It adds 42 tokens to every session and 465 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 2026-09-03.

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