skills

A portable package of instructions, scripts, and reference files that an AI coding agent can load when it needs a specific kind of help.

In plain words
What is it for?
It helps package domain knowledge, add repeatable task procedures, and provide scripts or documents for jobs such as expense processing, legal workflows, or data analysis.
Why use it?
It keeps specialised guidance separate from the agent’s main instructions and makes the same workflow reusable across compatible tools.

Agent

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 agents/managedcode/dotnet-skills/skills
Clone the repo
git clone --depth 1 https://github.com/managedcode/dotnet-skills
Per session 27 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 19,290 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 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 $0.00027 $0.19290
Opus 5 $0.00014 $0.09645
Sonnet 5 $0.00005 $0.03858
Haiku 4.5 $0.00003 $0.01929

Measured yesterday against content hash b9ccec42a44a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

skills 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 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.

Instruction-override phrasinghighPrompt injection

Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.

- **Review before use** - Read all skill content (`SKILL.md`, scripts, and resources) before deploying. Verify that a script's actual behavior matches its stated intent. Check for adversarial instructions that attempt to

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

result = subprocess.run(
catalog/Frameworks/Microsoft-Agent-Framework/skills/microsoft-agent-framework/references/official-docs/agents/skills.md · 2,090 lines

How it starts

The opening of the file, as written. The whole thing — 2,090 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Skills

Agent Skills are portable packages of instructions, scripts, and resources that give agents specialized capabilities and domain expertise. Skills follow an open specification and implement a progressive disclosure pattern so agents load only the context they need, when they need it.

Use Agent Skills when you want to:

  • Package domain expertise - Capture specialized knowledge (expense policies, legal workflows, data analysis pipelines) as reusable, portable packages.
  • Extend agent capabilities - Give agents new abilities without changing their core instructions.
  • Ensure consistency - Turn multi-step tasks into repeatable, auditable workflows.
  • Enable interoperability - Reuse the same skill across different Agent Skills-compatible products.

Skill structure

A skill is a directory containing a SKILL.md file with optional subdirectories for resources:

expense-report/
├── SKILL.md                          # Required - frontmatter + instructions
├── scripts/
│   └── validate.py                   # Executable code agents can run
├── references/
│   └── POLICY_FAQ.md                 # Reference documents loaded on demand
└── assets/
    └── expense-report-template.md    # Templates and static resources

SKILL.md format

The SKILL.md file must contain YAML frontmatter followed by markdown content:

---
name: expense-report
description: File and validate employee expense reports according to company policy. Use when asked about expense submissions, reimbursement rules, or spending limits.
license: Apache-2.0
compatibility: Requires python3
metadata:
  author: contoso-finance
  version: "2.1"
---
Field Required Description
name Yes Max 64 characters. Lowercase letters, numbers, and hyphens only. Must not start or end with a hyphen or contain consecutive hyphens. Must match the parent directory name.
description Yes What the skill does and when to use it. Max 1024 characters. Should include keywords that help agents identify relevant tasks.
license No License name or reference to a bundled license file.
compatibility No Max 500 characters. Indicates environment requirements (intended product, system packages, network access, etc.).
metadata No Arbitrary key-value mapping for additional metadata.
allowed-tools No Space-delimited list of pre-approved tools the skill may use. Experimental - support may vary between agent implementations.

Read the full file on GitHub · 2,090 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. yesterday First seen · 2,090 lines · 27 tokens per session scan C b9ccec42a44a

Subscribe to this mod's changes

skills is an agent published in the GitHub repository managedcode/dotnet-skills (477 stars, last pushed 2d ago), licensed MIT. It adds 27 tokens to every session and 19,290 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 2 findings (instruction-override phrasing, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.