graphql-and-hidden-parameters

graphql-and-hidden-parameters is a skill for Claude Code, Codex from JustineDevs/premortem. It costs 38 tokens per session (409 once invoked), scanned A, a copy of graphql-and-hidden-parameters, Apache-2.0.

A testing guide for finding weaknesses in GraphQL APIs, including hidden fields, undocumented inputs, and missing permission checks. GraphQL is an API format where clients ask for specific data through a shared schema.

In plain words
What is it for?
It is for checking GraphQL schema discovery, batched requests, hidden parameters, and authorization on nested or administrative data.
Why use it?
It helps reveal data or actions that the public documentation and visible interface do not show, including cases where users can access records or fields they should not.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit It is for checking GraphQL schema discovery, batched requests, hidden parameters, and authorization on nested or administrative data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/justinedevs/premortem/graphql-and-hidden-parameters
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 JustineDevs/premortem --skill graphql-and-hidden-parameters
Clone the repo
git clone --depth 1 https://github.com/JustineDevs/premortem

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 graphql-and-hidden-parameters

README.md
[![agentmods](https://agentmods.dev/badge/skills/justinedevs/premortem/graphql-and-hidden-parameters/github.svg)](https://agentmods.dev/skills/justinedevs/premortem/graphql-and-hidden-parameters)
Your own site
<a href="https://agentmods.dev/skills/justinedevs/premortem/graphql-and-hidden-parameters"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/graphql-and-hidden-parameters/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 graphql-and-hidden-parameters

Your own site · 80×15
<a href="https://agentmods.dev/skills/justinedevs/premortem/graphql-and-hidden-parameters"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/graphql-and-hidden-parameters.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 409 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 100% 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 5.1 $0.00038 $0.00409
Opus 5 $0.00019 $0.00204
Sonnet 5 $0.00008 $0.00082
Haiku 4.5 $0.00004 $0.00041

Measured 7d ago against content hash a8669e777739, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

graphql-and-hidden-parameters 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 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.

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

100% identical to graphql-and-hidden-parameters — 0 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.

.agents/skills/graphql-and-hidden-parameters/SKILL.md · 50 lines

What it actually says

SKILL: GraphQL and Hidden Parameters — Introspection, Batching, and Undocumented Fields

AI LOAD INSTRUCTION: Use this skill when GraphQL exists or when REST documentation suggests optional, deprecated, or undocumented fields. Focus on schema discovery, hidden parameter abuse, and batching as a force multiplier.

1. GRAPHQL FIRST PASS

query { __typename }
query {
  __schema {
    types { name }
  }
}

If introspection is restricted, continue with:

  • field suggestions and error-based discovery
  • known type probes like __type(name: "User")
  • JS and mobile bundle route extraction

2. HIGH-VALUE GRAPHQL TESTS

Theme Example
IDOR user(id: "victim")
batching array of login or object fetch operations
hidden fields admin-only fields exposed in type definitions
nested authz gaps related object fields with weaker checks

3. HIDDEN PARAMETER DISCOVERY

Look for:

  • fields present in admin docs but not public docs
  • additionalProperties or permissive schemas
  • frontend code using richer request bodies than visible UI controls
  • mobile endpoints carrying role, org, feature-flag, or internal filter fields

4. NEXT ROUTING

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 · 50 lines · 38 tokens per session scan A a8669e777739

Subscribe to this mod's changes

graphql-and-hidden-parameters is a skill published in the GitHub repository JustineDevs/premortem (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 38 tokens to every session and 409 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to graphql-and-hidden-parameters, differing in 0 lines, and is treated as a copy.

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