api-15-spec-injection

api-15-spec-injection is a skill for Claude Code, Codex from vigilantshield/Claude-HunterKit. It costs 60 tokens per session (971 once invoked), scanned C, original, no licence file.

A collection of techniques for testing APIs with strict rules about request fields and data formats. It covers unusual inputs such as extra parameters, JSON-to-XML or form changes, UTF-8 byte-order marks, and mismatched data types.

In plain words
What is it for?
Use it for security testing of APIs with strict schemas, including parameter pollution, content-type changes, parser bypasses, extra fields, and type confusion.
Why use it?
It helps reveal cases where an API validates requests differently than expected or where generated client code handles data unsafely. These tests are relevant when checking schema-validation and parser weaknesses.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it for security testing of APIs with strict schemas, including parameter pollution, content-type changes, parser bypasses, extra fields, and type confusion.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vigilantshield/claude-hunterkit/api-15-spec-injection
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 vigilantshield/Claude-HunterKit --skill api-15-spec-injection
Clone the repo
git clone --depth 1 https://github.com/vigilantshield/Claude-HunterKit

Made for: Claude Code, Codex.

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 api-15-spec-injection

README.md
[![agentmods](https://agentmods.dev/badge/skills/vigilantshield/claude-hunterkit/api-15-spec-injection.svg)](https://agentmods.dev/skills/vigilantshield/claude-hunterkit/api-15-spec-injection)
Your own site
<a href="https://agentmods.dev/skills/vigilantshield/claude-hunterkit/api-15-spec-injection"><img src="https://agentmods.dev/badge/skills/vigilantshield/claude-hunterkit/api-15-spec-injection.svg" alt="Measured on agentmods" height="20"></a>
Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 971 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00060 $0.00971
Opus 5 $0.00030 $0.00485
Sonnet 5 $0.00012 $0.00194
Haiku 4.5 $0.00006 $0.00097

Measured 7d ago against content hash 6fef78832b3e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

api-15-spec-injection scanned grade C with 2 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 7d 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- Send XML instead of JSON -->

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- curl / httpx
skills/api/api-15-spec-injection/SKILL.md · 133 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

1 file 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. 7d ago First seen · 133 lines · 60 tokens per session scan C 6fef78832b3e

Subscribe to this mod's changes

api-15-spec-injection is a skill published in the GitHub repository vigilantshield/Claude-HunterKit (5 stars, last pushed 1mo ago), with no licence file. It adds 60 tokens to every session and 971 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 2 findings (hidden instructions, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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