Cursor Skill (.mdc) Authoring

Cursor Skill (.mdc) Authoring is a skill for Claude Code, Codex from PramodDutta/qaskills. It costs 55 tokens per session (2,860 once invoked), scanned A, original, MIT.

A guide to writing Cursor rules: .mdc files that tell the Cursor AI editor how to work in particular files or situations. It explains the rule settings, scope, and structure needed to make those instructions apply correctly.

In plain words
What is it for?
Use it to create and improve Cursor rules for testing, code conventions, subagents, and file-specific workflows.
Why use it?
It helps prevent rules from activating too broadly, not activating at all, or becoming one large set of conflicting instructions. Small, targeted rules make AI-assisted coding behavior more predictable.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for aider. Also seen: mentions subagents; mentions Claude Code; mentions Codex.

Good fit Use it to create and improve Cursor rules for testing, code conventions…

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Install with agentmods
npx agentmods add skills/pramoddutta/qaskills/cursor-skill-authoring
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 PramodDutta/qaskills --skill cursor-skill-authoring
Clone the repo
git clone --depth 1 https://github.com/PramodDutta/qaskills

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 Cursor Skill (.mdc) Authoring

README.md
[![agentmods](https://agentmods.dev/badge/skills/pramoddutta/qaskills/cursor-skill-authoring.svg)](https://agentmods.dev/skills/pramoddutta/qaskills/cursor-skill-authoring)
Your own site
<a href="https://agentmods.dev/skills/pramoddutta/qaskills/cursor-skill-authoring"><img src="https://agentmods.dev/badge/skills/pramoddutta/qaskills/cursor-skill-authoring.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,860 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 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 5.1 $0.00055 $0.02860
Opus 5 $0.00028 $0.01430
Sonnet 5 $0.00011 $0.00572
Haiku 4.5 $0.00006 $0.00286

Measured 3d ago against content hash 7ea732ca9392, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

Cursor Skill (.mdc) Authoring 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 3d 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.

seed-skills/cursor-skill-authoring/SKILL.md · 250 lines

How it starts

The opening of the file, as written. The whole thing — 250 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cursor Skill (.mdc) Authoring Skill

You are an expert at writing Cursor rules - the .mdc files in .cursor/rules/ that steer Cursor's AI. When the user asks you to create or improve a Cursor rule (especially for testing/QA conventions), you write a correctly typed .mdc with valid YAML frontmatter, scope it precisely with globs, keep it short and imperative, and reference example files instead of pasting walls of code. You never write one giant catch-all rule; you write small, composable, well-scoped rules.

Core Principles

  1. .mdc lives in .cursor/rules/, not the legacy root file. Modern Cursor uses .cursor/rules/*.mdc. Nested rules in subfolders (packages/api/.cursor/rules/) scope to that part of the tree.
  2. The frontmatter fields decide when the rule fires. description, globs, and alwaysApply together select one of four rule types. Get these wrong and the rule never activates - or always does.
  3. Four rule types, one chosen by frontmatter. Always, Auto-Attached, Agent-Requested, and Manual. Pick deliberately; do not default everything to alwaysApply: true.
  4. description is the trigger for Agent-Requested rules. When alwaysApply is false and globs is empty, the model reads description to decide relevance. Write it as a clear "use this when..." sentence.
  5. Scope with globs, not prose. A rule that only matters for tests should be glob-scoped to **/*.test.ts, not a paragraph saying "only apply to tests."
  6. Keep rules short and imperative. Under ~500 lines, ideally far less. Bullet directives beat essays. The rule competes for the model's attention with the actual task.
  7. Reference files with @, do not paste them. @tests/example.spec.ts pulls in a canonical example on demand instead of bloating every prompt.
  8. One concern per rule file. A "Playwright conventions" rule and a "PR description format" rule are two files. Composable rules are easier to scope and maintain.

The Four Rule Types

Read the full file on GitHub · 250 lines

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. 3d ago First seen · 250 lines · 55 tokens per session scan A 7ea732ca9392

Subscribe to this mod's changes

Cursor Skill (.mdc) Authoring is a skill published in the GitHub repository PramodDutta/qaskills (217 stars, last pushed 7d ago), licensed MIT. It adds 55 tokens to every session and 2,860 once invoked, about $0.0003 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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