snomed-expert

snomed-expert is a skill for Claude Code from IHTSDO/snowstorm-mcp-server. It costs 65 tokens per session (2,542 once invoked), scanned A, original, Apache-2.0.

An expert workspace for SNOMED CT, a structured international system for recording clinical terms and concepts. It supports terminology specialists working with concepts, relationships, editions, and ECL queries, which are searches written in SNOMED CT's query language.

In plain words
What is it for?
Use it to write or run ECL searches, review concept modelling, compare editions, trace ancestors or descendants, inspect concept data, audit terminology quality, and validate value sets.
Why use it?
It helps specialists inspect and check complex clinical terminology data without manually tracing relationships or comparing releases.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Part of the snowstorm-mcp-server plugin — 2 skills, 1 MCP server shipped together

Good fit Use it to write or run ECL searches, review concept modelling, compare editions, trace ancestors or descendants, inspect concept data, audit terminology quality, and validate value sets.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ihtsdo/snowstorm-mcp-server/snomed-expert
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 IHTSDO/snowstorm-mcp-server --skill snomed-expert
Clone the repo
git clone --depth 1 https://github.com/IHTSDO/snowstorm-mcp-server

Made for: Claude Code.

Or install snowstorm-mcp-server, the plugin that ships this one along with the rest of its 2 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 snomed-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/ihtsdo/snowstorm-mcp-server/snomed-expert/github.svg)](https://agentmods.dev/skills/ihtsdo/snowstorm-mcp-server/snomed-expert)
Your own site
<a href="https://agentmods.dev/skills/ihtsdo/snowstorm-mcp-server/snomed-expert"><img src="https://agentmods.dev/badge/skills/ihtsdo/snowstorm-mcp-server/snomed-expert/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 snomed-expert

Your own site · 80×15
<a href="https://agentmods.dev/skills/ihtsdo/snowstorm-mcp-server/snomed-expert"><img src="https://agentmods.dev/badge/skills/ihtsdo/snowstorm-mcp-server/snomed-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 65 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,542 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00065 $0.02542
Opus 5 $0.00032 $0.01271
Sonnet 5 $0.00013 $0.00508
Haiku 4.5 $0.00006 $0.00254

Measured 11d ago against content hash 5250d77e6a4e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

snomed-expert scanned grade A with 1 finding 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 11d 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.

Makes network callslowCapability

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

**How to fetch:** Use `curl` or a web fetch tool with the full raw URL. Fetch the most specific file that covers the topic (e.g. `case-significance.md`, not the parent `README.md`). Strip GitBook-specific markup (`{% hin
skills/snomed-expert/SKILL.md · 149 lines

How it starts

The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a SNOMED CT expert assistant working with a knowledgeable user — a terminologist, clinical informaticist, or SNOMED CT editor, and using the SNOMED CT Terminology connector. Assume familiarity with ECL, concept model structure, description types, and the SNOMED CT release process.

The user has invoked this skill with: $ARGUMENTS

Clarify intent first

If $ARGUMENTS is empty, ask what they want to investigate. If an ECL expression or concept ID is provided, proceed directly. Common expert intents:

  • Run or refine ECL — they have an expression and want to execute or iterate on it
  • Audit concept modelling — inspect attributes, parents, and classification for a concept or set
  • Compare editions — check what is in a national edition vs. the International release, or compare release versions
  • Trace ancestry or descendants — full ancestor/descendant chains, not just one level
  • Spot terminology quality issues — duplicate synonyms, underspecified modelling, inactive concepts in active value sets
  • Inspect native concept data — full JSON representation including all descriptions, relationships, and axioms
  • Validate a value set — check all codes in a proposed set are active and correctly classified

How to proceed

Running or refining ECL

Pass the expression directly to snomed_expand. Use summary_only=true first to confirm the result count before fetching. If the result is larger than expected, offer to diagnose the expression before paginating. When helping write ECL:

  • Prefer << (descendant-or-self) over < unless the root concept itself should be excluded
  • Use MINUS to scope out unwanted subtrees rather than maintaining exclusion lists
  • Confirm the intended scope (International vs. national edition) before executing

Auditing concept modelling

Use snomed_lookup for human-readable attribute/parent summary, then snowstorm_get_concept_native for the full structured representation including OWL axioms and all description types. Surface:

  • Whether the concept has multiple parentage and whether that is clinically coherent
  • Any attributes that are more general than expected for the concept's position in the hierarchy
  • Inactive descriptions still referenced in active relationships (a known source of data quality issues)

Read the full file on GitHub · 149 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. 11d ago First seen · 149 lines · 65 tokens per session scan A 5250d77e6a4e

Subscribe to this mod's changes

snomed-expert is a skill published in the GitHub repository IHTSDO/snowstorm-mcp-server (8 stars, last pushed 21d ago), licensed Apache-2.0. It adds 65 tokens to every session and 2,542 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (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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