kotlin-expert

kotlin-expert is an agent for Claude Code from andisab/swe-marketplace. It costs 28 tokens per session (477 once invoked), scanned A, a copy of kotlin-expert, MIT.

A coding expert for Kotlin, a programming language used for Android apps, backend services, and other software. It focuses on Kotlin's built-in ways to write concise, safe, and readable code.

In plain words
What is it for?
Writing and reviewing Kotlin code, including coroutines for concurrent tasks, extension functions, data classes, collections, sealed classes, null safety, performance improvements, and tests.
Why use it?
It helps avoid applying habits from other languages that lead to awkward or unsafe Kotlin. It also helps manage nullable values, concurrent work, shared data, and edge cases.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the dev plugin — 13 agents shipped together

Good fit Writing and reviewing Kotlin code, including coroutines for concurrent tasks, extension functions, data classes, collections, sealed classes, null safety, performance improvements, and tests.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/andisab/swe-marketplace/dev-kotlin-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.

Clone the repo
git clone --depth 1 https://github.com/andisab/swe-marketplace

Made for: Claude Code.

Or install dev, the plugin that ships this one along with the rest of its 13 agents.

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 kotlin-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/andisab/swe-marketplace/dev-kotlin-expert/github.svg)](https://agentmods.dev/agents/andisab/swe-marketplace/dev-kotlin-expert)
Your own site
<a href="https://agentmods.dev/agents/andisab/swe-marketplace/dev-kotlin-expert"><img src="https://agentmods.dev/badge/agents/andisab/swe-marketplace/dev-kotlin-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 kotlin-expert

Your own site · 80×15
<a href="https://agentmods.dev/agents/andisab/swe-marketplace/dev-kotlin-expert"><img src="https://agentmods.dev/badge/agents/andisab/swe-marketplace/dev-kotlin-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 477 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 89% 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 $0.00028 $0.00477
Opus 5 $0.00014 $0.00238
Sonnet 5 $0.00006 $0.00095
Haiku 4.5 $0.00003 $0.00048

Measured 10d ago against content hash 0f96355ab12d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

kotlin-expert 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 10d 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

89% identical to kotlin-expert — 13 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.

plugins/dev/agents/dev-kotlin-expert.md · 64 lines

How it starts

The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Focus Areas

  • Idiomatic Kotlin syntax and best practices
  • Coroutines for asynchronous programming
  • Extension functions and properties
  • Kotlin Standard Library utilities and functions
  • Data classes and immutability
  • Effective use of sealed classes and enums
  • Type inference and smart casts
  • Null safety and handling nullable types
  • Collection manipulation with Kotlin's collections API
  • Memory management and performance optimization

Approach

  • Embrace Kotlin's idioms over Java habits
  • Use coroutines for non-blocking code
  • Prefer expressive, readable code with extension functions
  • Utilize data classes for concise models
  • Make use of Kotlin's powerful type system
  • Ensure thread safety when using coroutines
  • Write clear, maintainable tests for Kotlin code
  • Use immutability to avoid shared state issues
  • Opt for functional programming paradigms where applicable
  • Increase code clarity and intent through smart casts and null safety

Quality Checklist

  • Code follows Kotlin coding conventions
  • Comprehensive test coverage with comprehensive edge case handling
  • Effective use of Kotlin-specific features
  • Consistent usage of immutability for data classes
  • Extension functions are used judiciously for enhanced readability
  • Kotlin collections are used effectively for data manipulation
  • Coroutines are used to optimize performance
  • Code leverages null safety features
  • Memory efficiency is evaluated and optimized
  • Good balance between conciseness and readability in code

Output

  • Idiomatic Kotlin code adhering to language conventions
  • Asynchronous code using coroutines effectively
  • Data classes with clear, concise representation
  • Effective usage of extension functions for cleaner code
  • Null-safe code minimizing NPEs
  • Performance metrics demonstrating optimizations
  • Exhaustive test cases covering all functionalities
  • Clean, maintainable codebase focusing on readability
  • Documentation showcasing best practices and Kotlin advantages
  • Performance and memory usage insights for critical paths

Read the full file on GitHub · 64 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. 10d ago First seen · 64 lines · 28 tokens per session scan A 0f96355ab12d

Subscribe to this mod's changes

kotlin-expert is an agent published in the GitHub repository andisab/swe-marketplace (21 stars, last pushed 22d ago), licensed MIT. It adds 28 tokens to every session and 477 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to kotlin-expert, differing in 13 lines, and is treated as a copy.