add-skill

add-skill is a skill for Claude Code from cyanheads/medical-codes-mcp-server. It costs 95 tokens per session (2,523 once invoked), scanned A, a copy of add-skill, Apache-2.0.

An authoring guide for publishing an agent skill: a root `skills/SKILL.md` file that follows the Agent Skills specification and can be discovered and packaged by plugin hosts.

In plain words
What is it for?
Use it to write, validate, and publish an agent guide containing procedures, identifier chains, safety checks, or query syntax.
Why use it?
It prevents skills from being ignored because they are in the wrong tree or fail packaging checks. It also explains when a separate skill is needed instead of repeating tool descriptions.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions .claude-plugin; mentions Claude Code; mentions Codex.

Part of the medical-codes-mcp-server plugin — 35 skills, 1 MCP server shipped together

Good fit Use it to write, validate, and publish an agent guide containing procedures, identifier chains, safety checks, or query syntax.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cyanheads/medical-codes-mcp-server/add-skill
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 cyanheads/medical-codes-mcp-server --skill add-skill
Clone the repo
git clone --depth 1 https://github.com/cyanheads/medical-codes-mcp-server

Made for: Claude Code.

Or install medical-codes-mcp-server, the plugin that ships this one along with the rest of its 35 skills, 1 MCP server.

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 add-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/cyanheads/medical-codes-mcp-server/add-skill/github.svg)](https://agentmods.dev/skills/cyanheads/medical-codes-mcp-server/add-skill)
Your own site
<a href="https://agentmods.dev/skills/cyanheads/medical-codes-mcp-server/add-skill"><img src="https://agentmods.dev/badge/skills/cyanheads/medical-codes-mcp-server/add-skill/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 add-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/cyanheads/medical-codes-mcp-server/add-skill"><img src="https://agentmods.dev/badge/skills/cyanheads/medical-codes-mcp-server/add-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 95 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,523 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 $0.00095 $0.02523
Opus 5.5 $0.00038 $0.01009
Sonnet 5.5 $0.00019 $0.00505
Haiku 4.5 $0.00010 $0.00252

Measured 2d ago against content hash 0d4497574def, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

add-skill 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 2d 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 add-skill — 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.

framework-skills/add-skill/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Context

A server has two skill trees, written for different readers:

Tree Reader Written by
framework-skills/ The agent building the server init and the maintenance sync, plus any development skills of the server's own
skills/ (root) The agent that installed the server and is calling its tools The author, deliberately

Root skills/ is absent by default; init and maintenance never write it. Claude Code always scans a plugin's root skills/ (Agent Plugins 1.0.0 fixes discovery there), so no skills field is needed in .claude-plugin/plugin.json. Each SKILL.md follows the Agent Skills specification; a host skips one that doesn't, without a word, which is why lint:packaging validates the tree.

No skill by default

Publish one only when an agent calling the tools needs something instructions and tool descriptions cannot carry: a multi-hop identifier chain, a gate that prevents a wrong call or a wrong conclusion, a query syntax. Overview skills that restate the tool list, generic "how to use this server" workflows, and skills for hypothetical tasks do not ship.

Authoring rules

  • Perspective. The reader is the agent calling the server's tools in the middle of a multi-step task, not the maintainer. Walk a realistic workflow against the tool surface and write down what that agent needs at each hop.
  • One skill per server, split by trigger. The description stays resident in every session; the body loads only on invocation, so workflows belong inside the one skill, not in a second with the same trigger. A second skill earns its place only when a distinct trigger vocabulary routes to a materially different workflow. Two is the cap; three when day-to-day use of the server proves it.
  • Naming. Default <package short name>-guide (pubmed-guide for pubmed-mcp-server). The description names the tool prefix (pubmed_*) so the agent binds the skill to the tools it sees.
  • Layering. Tool .describe() text carries the per-tool contract; instructions carries a one-paragraph orientation (canonical chain, identifier types, rate posture); MCP prompts stay user-invoked task templates. The skill carries what none of those can: when to reach for the server and when not to, where each opaque identifier comes from, gates, branching workflows, and syntax references. It never restates instructions.
  • Gates are the section a skill exists for. Each is an imperative the agent satisfies before acting or concluding: a precondition (resolve a name to an ID before filtering, where an unresolved filter returns the global set), a stop rule (confirm coverage before reporting a record absent), or a confirmation gate (ask the user before a tool that sends, writes, or deletes). Verified facts only, sourced from instructions, the design doc's Workflow Analysis and Known Limitations, tool descriptions, or closed issues — nothing invented. Cut any fact that would not change what the agent does.
  • Drift. Name tools in prose; never list their parameters — the schemas own them.
  • Budget. SKILL.md under 150 lines (the specification's 500 is a ceiling, not a target); the description under 500 characters, since it is resident in every session. Long material goes to references/.

Read the full file on GitHub · 139 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. 2d ago First seen · 139 lines · 95 tokens per session scan A 0d4497574def

Subscribe to this mod's changes

add-skill is a skill published in the GitHub repository cyanheads/medical-codes-mcp-server (2 stars, last pushed today), licensed Apache-2.0. It adds 95 tokens to every session and 2,523 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to add-skill, differing in 0 lines, and is treated as a copy.

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