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MPS: Skill for Claude Code

.agents/skills/mps-language-analysis/SKILL.md

mps-language-analysis is a skill for Claude Code, Codex from JetBrains/MPS. It costs 94 tokens per session (1,773 once invoked), scanned A, original, Apache-2.0.

An analysis guide for JetBrains MPS languages, which are custom languages built inside the MPS development environment. It maps their concepts, properties, relationships, editors, rules, behaviours, and metadata.

In plain words
What is it for?
Use it to inspect a language's structure, find concepts and examples, understand editor and constraint aspects, and obtain precise concept names for model blueprints.
Why use it?
It helps developers understand an unfamiliar MPS language before editing models or creating new language elements.

Skill for Claude CodeCodex ✓ vendor

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

This is JetBrains/MPS's own configuration. It tells Claude Code and Codex how to work on MPS itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything MPS configures →

not rated 1.7krepo +4 changed 8d ago A scan SkillSpector: pass 94 tokens original Apache-2.0
View source ↗ JetBrains/MPS jetbrains.com
About the project

JetBrains MPS is a development environment for creating domain-specific languages, which are programming languages designed for a particular field or task. It provides editors with features such as completion, semantic checks, and type checking, and can generate code in languages including Java and XML.

JetBrains/MPS · 1,666 stars · on GitHub · jetbrains.com

Reuse

Borrowing it

Nothing to install: this file belongs to JetBrains/MPS. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/JetBrains/MPS/master/.agents/skills/mps-language-analysis/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/JetBrains/MPS

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.

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README.md
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Your own site
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Your own site · 80×15
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Per session 94 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,773 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00094 $0.01773
Opus 5.5 $0.00038 $0.00709
Sonnet 5.5 $0.00019 $0.00355
Haiku 4.5 $0.00009 $0.00177

Measured 8d ago against content hash 2dc1a0fb4f46, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mps-language-analysis 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 8d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/concept_shape.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

.agents/skills/mps-language-analysis/SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MPS Language Analysis

Loading companion skills

Companion names in this skill are lazy dependencies: load only those relevant to the current task. If this skill came from an MCP server, use the host's skill loader to resolve the companion's unique discovered entry URI on the same host-assigned originating server. If the host has no server-backed skill loader, stop and report that limitation; do not silently fall back to a filesystem copy. If this skill came from a filesystem catalog, load the named sibling from that same catalog at <skills-root>/<skill-name>/SKILL.md, even if remote skill loaders are also available. Do not invent a tool name or server endpoint.

Workflow for inspecting an MPS language from a name (e.g. jetbrains.mps.lang.core). Returns concepts, metadata, structural info, and pointers to declarations and sample nodes.

Critical Directives

  • Use the fully qualified language name (e.g. jetbrains.mps.lang.core) — single-letter shorthand (j.m.l.core) requires resolution first via mps_mcp_get_project_structure.
  • For the qualifiedName returned by mps_mcp_get_concept_details, use it as the concept field in JSON blueprints. It is unambiguous.

Analyzing a Language by Name

  1. Verify Language: call mps_mcp_get_project_structure with the language name as a filter (startingPoint: My_Language). This confirms existence and provides the UUID.
  2. Retrieve Concepts: use mps_mcp_get_concept_details with the language name in languageRefs. Both conceptRefs and languageRefs accept either one value or a JSON array (real or written as a string); omit the unused selector.
  3. Extract Data: the response includes:
    • Name: concept FQN.
    • Description: found in shortDescription.
    • Metadata: isRootable, isAbstract, and the conceptReference ID.
    • Structure: properties, children, and references are detailed here.
  4. Drill Down:
    • Declaration: use the sourceNode reference with mps_mcp_open_node to open the definition.
    • Examples: use mps_mcp_query_nodes with FIND_INSTANCES (sampleOnly: true) to get a sample node. Then use mps_mcp_print_node to see its canonical JSON structure for use as a template.
    • Inheritance: load the mps-language-inheritance skill for deeper hierarchy analysis.

Read the full file on GitHub · 87 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago Changed · +1 lines 2dc1a0fb4f46
  2. 29d ago Changed · +4 lines · +37 tokens per session 0e6c6561d30a
  3. 1mo ago Changed · +31 lines e59f09fef379
  4. 2mo ago First seen · 51 lines · 57 tokens per session scan A 2c15f7ac74bb

Subscribe to this mod's changes

mps-language-analysis is a skill published in the GitHub repository JetBrains/MPS (1,666 stars, last pushed yesterday), licensed Apache-2.0. It adds 94 tokens to every session and 1,773 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-08-30.

Languagesdomain-specific-languagedsl
Related

mps-language-analysis compared with skills from other repositories

mps-language-analysis next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
mps-language-analysisJetBrains/MPSSkill1.7kyesterdayApache-2.0A94Claude Code, Codex
langiumeclipse-langium/langium-aiSkill314d agoMITA33Claude Code
lai-gen-descriptoreclipse-langium/langium-aiSkill314d agoMITA49Claude Code
lai-gen-mcpeclipse-langium/langium-aiSkill314d agoMITA43Claude Code
lai-gen-language-skilleclipse-langium/langium-aiSkill314d agoMITA33Claude Code
triton-syntaxmindspore-ai/akgSkill2652d agoApache-2.0A21Claude Code, Codex
triton-ascendmindspore-ai/akgSkill2652d agoApache-2.0A28Claude Code, Codex