MCP Steroid Project Assessment: 75 Days, 1300+ Commits, One Plugin

I decided to take a step back and look at what has been built so far.

MCP Steroid started on December 10, 2025. It is an IntelliJ Platform plugin that exposes the full IDE JVM runtime to AI Agents via the Model Context Protocol. Instead of reading and writing files, agents can compile code, run inspections, trigger refactorings, use the debugger, and take screenshots – all through one MCP tool that executes Kotlin inside the IDE’s JVM – a much more flexible, powerful, and minimalistic API an AI Agent can use.

75 days later, the numbers tell an interesting story.

The numbers

Metric Value
Total commits 1,306
Active development days 52 of 75 (69% utilization)
Avg commits per active day ~25
Production Kotlin LOC 27,505
Test Kotlin LOC 110,482
Test-to-production ratio 4:1
Gradle submodules 8
Releases 3 (0.87.0, 0.88.0, 0.89.0)

The 4:1 test-to-production ratio is not an accident. The Docker-based integration tests launch a full IntelliJ IDE in a container, connect real AI Agents (Claude Code, Codex, Gemini CLI), and verify end-to-end MCP workflows. Arena tests run curated project benchmarks comparing agent performance with and without the plugin.

Architecture highlights

The core execution pipeline follows a two-phase design: compile first with an external kotlinc process, then run the compiled code inside the IDE’s JVM with coroutine-based timeout enforcement. This separation means agents get compilation errors immediately without waiting for execution.

A few technical decisions that turned out well:

  • Modal dialog race detection – Kotlin select{} races script execution against IDE dialog appearance. If a dialog pops up mid-execution, the script cancels and a screenshot goes back to the agent.
  • External Kotlin compiler isolation – agent scripts cannot starve the IDE’s own Kotlin daemon. The plugin recovers automatically when the daemon dies.
  • Transport-agnostic MCP core – the JSON-RPC dispatcher has zero HTTP dependencies. The Ktor transport layer is pluggable.
  • Append-only execution storage – every script, compilation output, and result is stored as an immutable audit trail under .idea/mcp-steroid/.

Quality scorecard

Dimension Score
Code Organization 9/10
Error Handling 9/10
Test Coverage 8.5/10
Architectural Sophistication 9/10
Coroutine Patterns 9.5/10
IntelliJ Platform Integration 9/10
Extensibility 9/10
Overall 8.8/10

Zero runBlocking() in production code. Proper readAction{}/writeAction{} threading. ProcessCanceledException always rethrown. IntelliJ service model used correctly throughout.

What makes this unique

MCP Steroid is the only product that gives AI Agents visual IDE access – screenshots with component trees, keyboard and mouse input dispatch, OCR integration. Agents operate at the same level of semantic understanding that the IDE itself uses: type-aware symbol search, real inspections, IDE-native refactorings, live test results.

The plugin works with Claude Code, OpenAI Codex, and Google Gemini CLI today. Human-in-the-loop review gates are configurable per project.

Where it is heading

Multi-IDE support is already underway (GoLand, WebStorm). The NPX proxy aggregates multiple IDE instances. The arena benchmarking framework measures agent quality across curated project scenarios. Enterprise deployment works via a custom plugin repository.

Update: v0.89.0 released

Three days after this assessment, version 0.89.0 shipped – 361 commits since 0.88.0.

Key highlights:

  • Codex agent output support – full NDJSON format handling for OpenAI Codex, including mcp_tool_call items, structured results, and reasoning blocks. Raw and decoded agent logs are saved per prompt run.
  • Prompt system overhaul – all prompt articles migrated to single-file .md format with auto-generated TOC and per-article read tests.
  • DPAIA arena testing – Docker-based A/B comparison framework that measures agent effectiveness with and without MCP Steroid on curated project scenarios.
  • Settings UI – new project settings page under Tools > MCP Steroid with copy buttons and structured connection info.
  • Claude Code 2.1.x compatibility – handles both old streaming and new structured event formats.
  • Stability fixes – resolved an 8-minute startup deadlock in Docker containers, fixed onboarding dialogs blocking test runs, and several NPE fixes.

Full release notes: v0.89.0 on the MCP Steroid site.

AI Agents can debug now

The debugger integration is what sets MCP Steroid apart from every other AI coding tool. No other product gives AI Agents access to breakpoints, step-over, variable inspection, and expression evaluation inside a real IDE debugger.

Here is Codex debugging an application in IntelliJ IDEA, powered by MCP Steroid:

And a shorter demo showing the debugger workflow – setting breakpoints, stepping through code, evaluating expressions:

Try MCP Steroid

If you are building with AI Agents and want to give them the full IDE – not just file access, but compilation, inspections, refactorings, debugging, and visual understanding – give MCP Steroid a try.

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