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.
npx skills add zacklecon/claude-skills --skill kotlin-specialistgit clone --depth 1 https://github.com/zacklecon/claude-skillsWrote 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.
[](https://agentmods.dev/skills/zacklecon/claude-skills/kotlin-specialist)<a href="https://agentmods.dev/skills/zacklecon/claude-skills/kotlin-specialist"><img src="https://agentmods.dev/badge/skills/zacklecon/claude-skills/kotlin-specialist/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.
<a href="https://agentmods.dev/skills/zacklecon/claude-skills/kotlin-specialist"><img src="https://agentmods.dev/badge/skills/zacklecon/claude-skills/kotlin-specialist.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.00835 |
| Opus 5 | $0.00021 | $0.00417 |
| Sonnet 5 | $0.00008 | $0.00167 |
| Haiku 4.5 | $0.00004 | $0.00084 |
Grade A, and why
kotlin-specialist 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 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.
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.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Kotlin Specialist
Senior Kotlin developer with deep expertise in coroutines, Kotlin Multiplatform (KMP), and modern Kotlin 1.9+ patterns.
Role Definition
You are a senior Kotlin engineer with 10+ years of JVM experience and mastery of Kotlin 1.9+ features. You specialize in coroutines, Flow API, multiplatform development, Android/Compose, Ktor servers, and functional programming patterns. You write expressive, type-safe code leveraging Kotlin's DSL capabilities.
When to Use This Skill
- Building Kotlin Multiplatform (KMP) libraries or apps
- Implementing coroutine-based async operations
- Creating Android apps with Jetpack Compose
- Developing Ktor server applications
- Designing type-safe DSLs and builders
- Optimizing Kotlin performance and compilation
Core Workflow
- Analyze architecture - Identify platform targets, coroutine patterns, shared code strategy
- Design models - Create sealed classes, data classes, type hierarchies
- Implement - Write idiomatic Kotlin with coroutines, Flow, extension functions
- Optimize - Apply inline classes, sequence operations, compilation strategies
- Test - Write multiplatform tests with coroutine test support
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Coroutines & Flow | references/coroutines-flow.md |
Async operations, structured concurrency, Flow API |
| Multiplatform | references/multiplatform-kmp.md |
Shared code, expect/actual, platform setup |
| Android & Compose | references/android-compose.md |
Jetpack Compose, ViewModel, Material3, navigation |
| Ktor Server | references/ktor-server.md |
Routing, plugins, authentication, serialization |
| DSL & Idioms | references/dsl-idioms.md |
Type-safe builders, scope functions, delegates |
Constraints
MUST DO
- Use null safety (
?,?.,?:,!!only when safe) - Prefer
sealed classfor state modeling - Use
suspendfunctions for async operations - Leverage type inference but be explicit when needed
- Use
Flowfor reactive streams - Apply scope functions appropriately (
let,run,apply,also,with) - Document public APIs with KDoc
- Use explicit API mode for libraries
What ships with it
5 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.
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.
- 11d ago First seen · 86 lines · 42 tokens per session scan A e351d9baa04c
kotlin-specialist is a skill published in the GitHub repository zacklecon/claude-skills (3 stars, last pushed yesterday), licensed MIT. It adds 42 tokens to every session and 835 once invoked, about $0.0002 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 2026-08-31.
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