Mcp Steroid

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MCP Steroid

Give AI the whole IntelliJ, not just the files AI agents can finally SEE your IDE — not just read code

Website • Demo Videos • Blog Post • Discord

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About MCP Steroid

MCP Steroid is an open-source Model Context Protocol server that runs inside JetBrains IDEs and exposes the full power of the IntelliJ Platform to AI agents.

Unlike file-only assistants, MCP Steroid gives AI agents the same capabilities developers use: semantic code understanding, advanced refactorings, debugging, test running, visual awareness, and the entire IntelliJ API surface.

There are two ways to run it. Start with the new devrig CLI (preview): a standalone tool that bridges any MCP-capable agent into a real IntelliJ-family IDE over stdio — through one bridge it connects to every IDE you already have open at once (across projects), or downloads, installs, and starts one for the agent (great for headless, CI, and fresh machines). Or run the JetBrains IDE plugin in-IDE over HTTP. The project is gradually moving toward the Devrig name.

One bridge, every IDE

A single devrig process connects your AI Agent to all the IntelliJ-family IDEs running on your machine at once — each open on a different project — and can download and start more on demand.

What Makes It Unique

MCP Steroid is the only MCP server offering ALL of:

• Visual IDE understanding — Screenshots + OCR + component tree
• UI automation — Control the IDE like a human developer
• Native IntelliJ APIs — PSI, inspections, refactorings, and more
• Kotlin scripting — Full platform access at runtime
• Standard MCP protocol — Works with ANY MCP-compatible AI agent

Benchmarks

On DPAIA Spring Boot tasks, agents with MCP Steroid are 20–54% faster than file-only workflows on complex multi-file operations:

| Case | Task | MCP Time | No-MCP Time | Δ | |------|------|----------|-------------|---------| | dpaia\jhipster\sample\app-3 | Rename ROLEADMIN across app (9 files) | 202s | 440s | -54% | | dpaia\empty\maven\springboot3-1 | JWT auth from scratch (5+ new files) | 288s | 396s | -27% | | dpaia\feature\service-25 | Parent-child JPA + Flyway (10 files) | 382s | 523s | -27% | | dpaia\feature\service-125 | Multi-layer JPA+service+controller (15 files) | 788s | 1002s | -21% | | dpaia\spring\petclinic\rest-14 | Simple URL prefix replace (7 files) | 188s | 181s | +4% | | dpaia\train\ticket-1 | Extend OrderRepository JPQL (4 files) | 727s | 633s | +15% |

Tasks requiring semantic understanding show the largest speed gains. Simple text replacements perform similarly with or without IDE access.

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Install

Requirements: IntelliJ IDEA 2026.1+ (or any IntelliJ-based IDE: Rider, Android Studio, GoLand, WebStorm, PyCharm, CLion, etc.)

JetBrains Marketplace

Search for MCP Steroid in Settings > Plugins > Marketplace, or install from plugins.jetbrains.com.

Custom Plugin Repository (recommended for faster updates)

Add this URL in Settings > Plugins > Gear icon > Manage Plugin Repositories...:

https://mcp-steroid.jonnyzzz.com/updatePlugins.xml

Manual Download

Download the latest ZIP from GitHub Releases and install via Settings > Plugins > Gear icon > Install Plugin from Disk.

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Connect Your AI Agent

devrig is the standalone CLI for connecting agents to MCP Steroid. It runs a stdio MCP bridge and connects your agent to every running IntelliJ instance at once (across projects), discovered automatically — and when none is open it can download, prepare, and start a managed IDE backend for the agent (IDEA Community/Ultimate, PyCharm, Android Studio). It's the recommended way to wire up Claude Code, Codex CLI, and Gemini CLI — one registration per agent, applies to every project on the machine.

> Requirement: JDK 25. devrig is a Kotlin/JVM application compiled for Java 25 (class-file v69) and is not bundled with a JRE. A JDK/JRE 25 or newer must be available on the machine that runs it — either on PATH or via JAVA_HOME (the devrig launcher honours JAVA_HOME first). An older Java (21, etc.) fails at startup with UnsupportedClassVersionError ... class file version 69.0. Install e.g. Amazon Corretto 25 or Eclipse Temurin 25, and point JAVA_HOME at it if your default java is older.

One-time setup (from a checkout of this repo)

# Build :npx-kt:installDist and stage the launcher under ~/.mcp-steroid/devrig/
./gradlew deployNpx

# Register `mcp-steroid` (stdio) at user scope for each agent — once per machine.
# The first call (run by full path, since devrig is not on PATH yet) self-installs the stable
# launcher ~/.mcp-steroid/bin/devrig, links it onto PATH as `devrig`, and registers THAT — so
# registrations survive devrig upgrades. Use `devrig` (a fresh shell picks it up) thereafter.
~/.mcp-steroid/devrig/bin/devrig install claude
devrig install codex
devrig install gemini

Each install call delegates to the agent's own mcp add CLI, so the entry lands in the user-scope config (~/.claude.json, ~/.codex/config.toml, ~/.gemini/settings.json) and is visible from every project.

Refreshing the launcher

After pulling new commits, run ./gradlew deployNpx again. It rebuilds :npx-kt:installDist and re-syncs ~/.mcp-steroid/devrig/ — the launcher path stays the same, so no re-registration is needed. Runtime state under ~/.mcp-steroid/{backends,caches,logs,markers,state} is preserved.

Verifying it works

claude mcp list                                 # mcp-steroid: ... - ✓ Connected
claude -p "List all open projects using steroid_list_projects"

The plugin also writes the raw server URL to .idea/mcp-steroid.md in each open project at http://127.0.0.1:6315/mcp (Streamable HTTP transport) for clients that prefer to talk to the IDE directly.

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Compatible AI Agents

Works with ANY MCP-compatible client:

• Claude (Claude Code, Claude Desktop)
• ChatGPT with MCP support
• Gemini CLI
• Codex CLI
• Cursor IDE
• Junie
• OpenCode
• Any other MCP-compatible client

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Capabilities

Design philosophy in one breath

The MCP tool surface is intentionally small — power lives in mcp-steroid:// prompt resources that teach agents to call IntelliJ's APIs directly inside steroid_execute_code. New tools and new McpScriptContext methods are not the lever for "agents deliver more"; better recipes are. The full canonical statement lives in [docs/PHILOSOPHY.md](docs/PHILOSOPHY.md) and is mirrored at runtime as mcp-steroid://skill/design-philosophy.

8 MCP Tools

| Tool | Description | |------|-------------| | Execute Code (steroid_execute_code) | Run Kotlin code inside the IDE's JVM with full API access | | Execute Feedback (steroid_execute_feedback) | Provide execution ratings back to agents | | Fetch Resource (steroid_fetch_resource) | Fetch any mcp-steroid:// skill guide / recipe by URI | | Vision Screenshot (steroid_take_screenshot) | Capture IDE screenshots with component metadata | | Vision Input (steroid_input) | Send keyboard/mouse events to the IDE via a sequence-string DSL | | List Projects (steroid_list_projects) | Discover all open IntelliJ projects | | List Windows (steroid_list_windows) | Enumerate IDE windows and components | | Open Project (steroid_open_project) | Open projects programmatically |

58 MCP Resources

Comprehensive guides and examples covering:

• LSP Operations (11) — Go to definition, find references, hover, completion
• IDE Power Operations (22) — Refactorings, code generation, project analysis
• Debugger Integration (7) — Breakpoints, thread control, debugging workflows
• Test Runner (10) — Run tests, inspect results, navigate test trees
• VCS Operations (3) — Git annotations, file history
• Project Workflows (4) — Open projects with trust levels
• Skill Guides (3) — IntelliJ API, debugger, and test runner guides

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Featured Demo Videos

| Video | Description | Duration | |-------|-------------|----------| | Codex Debugs in IntelliJ IDEA | Full debugging session with Codex | 1:03:24 | | CodeDozer Demo 5 | Most popular demo | 1:00 | | CodeDozer & IntelliJ Debugger | Debugger integration showcase | 8:25 | | Now we call tasks in IntelliJ | Task execution demo | 2:21 | | Real Work in Monorepo Part 2 | Deep dive into real workflow | 18:37 | | Cursor Talks with IntelliJ | Cursor integration | 0:44 |

Watch all demos: MCP Steroid Playlist

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Configuration

MCP Steroid can be configured via IntelliJ's Registry (Help > Find Action > Registry) or JVM system properties.

| Registry Key | Default | Description | |--------------|---------|-------------| | mcp.steroid.server.port | 6315 | MCP server port (0 for auto-assign) | | mcp.steroid.server.host | 127.0.0.1 | Bind address (use 0.0.0.0 for Docker) | | mcp.steroid.storage.path | (empty) | Custom storage path (default: .idea/mcp-steroid/) |

See the full Configuration Documentation on the website.

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Architecture

• Technology: Kotlin 2.3.20 on Java 25
• HTTP Server: Ktor 3.1.0 (Streamable HTTP + SSE)
• Protocol: Model Context Protocol (MCP)
• Default Port: 6315
• OCR: Tesseract 5.5.1
• Platform: IntelliJ Platform Plugin SDK

The server runs inside the IDE's JVM process — no inter-process communication. Direct access to the project model, semantic index, PSI tree, test runner, debugger, and VCS layer.

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About the Project

MCP Steroid is an open-source project by Eugene Petrenko (@jonnyzzz), licensed under [Apache 2.0](LICENSE).

Read more:

• MCP Steroid Is Now Open Source — announcement and project history
• IntelliJ as a Skill Factory — build custom agent skills without plugin development
• Project Assessment: 75 Days, 1300+ Commits — architecture and quality deep dive

IntelliJ IDEA, IntelliJ Platform, PyCharm, WebStorm, and JetBrains are trademarks of JetBrains s.r.o.

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Contributing

We welcome contributions! See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines on how to get started, and [CONTRIBUTORS.md](CONTRIBUTORS.md) for the list of people who have helped make MCP Steroid better.

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License

MCP Steroid is open-source software licensed under the [Apache License 2.0](LICENSE).

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Links

• Website: mcp-steroid.jonnyzzz.com
• JetBrains Marketplace: plugins.jetbrains.com
• Discord: discord.gg/e9qgQ7NeTC
• GitHub Issues: github.com/jonnyzzz/mcp-steroid/issues
• GitHub Sponsors: github.com/sponsors/jonnyzzz
• Blog: jonnyzzz.com
• YouTube: @jonnyzzz
• LinkedIn: jonnyzzz
• X/Twitter: @jonnyzzz

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Built with care for the AI agent developer community

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: jonnyzzz
• Source: jonnyzzz/mcp-steroid
• License: Apache-2.0
• Homepage: https://mcp-steroid.jonnyzzz.com

Install and usage instructions live in the source repository linked above.