Debugger MCP Server

A JetBrains IDE plugin that exposes an MCP (Model Context Protocol) server, giving AI coding assistants full programmatic control over the debugger. Set breakpoints, step through code, inspect variables, and evaluate expressions—all driven autonomously by your AI assistant.

Fully tested: IntelliJ IDEA, PyCharm, WebStorm, GoLand, RustRover, Android Studio, PhpStorm May work (untested): RubyMine, CLion, DataGrip

Debugger MCP Server gives AI coding assistants complete control over the IDE's debugger through the Model Context Protocol (MCP). Let your AI assistant debug code autonomously—from setting breakpoints to inspecting variables to stepping through execution.

Features

Debug Session Management

Start/Stop Sessions - Launch any run configuration in debug mode
Rich Status - Get comprehensive state in a single call (variables, stack, source context)
Multi-Session Support - Manage multiple concurrent debug sessions

Breakpoint Management

Line Breakpoints - Set breakpoints at any valid location
Conditional Breakpoints - Add conditions that must be true to pause
Tracepoints - Log messages without pausing execution

Execution Control

Step Over/Into/Out - Navigate through code line by line
Resume & Pause - Control execution flow
Run to Line - Continue execution until a specific line

Variable Inspection

View Variables - Inspect local variables, arguments, and object fields
Modify Values - Change variable values during debugging

Expression Evaluation

Evaluate Expressions - Run arbitrary expressions in the current context
Code Fragments - Execute multi-line code snippets

Stack & Thread Navigation

Stack Traces - View the complete call stack with source locations
Frame Selection - Switch context to any stack frame
Thread Listing - See all threads and their states

Companion Skill

AI Debugging Guidance - Bundled companion skill teaches AI agents optimal debugger tool usage
One-Click Install - Install to .claude/skills/ or export as .skill/.zip

Why Use This Plugin?

Unlike manual debugging, this plugin enables:

Autonomous AI Debugging - Your AI assistant can debug code without human intervention
Rich Context in Single Calls - Get variables, stack, and source in one request
Programmatic Breakpoint Control - Set conditional breakpoints with complex expressions
Cross-IDE Compatibility - Works with any JetBrains IDE that supports XDebugger
22 Comprehensive Tools - Full debugging capability through MCP
Configurable Server - IDE-specific ports with customizable host binding

Perfect for AI-assisted development workflows where you want your assistant to investigate bugs, validate fixes, or explore code behavior autonomously.

Installation

Using the IDE built-in plugin system

Settings/Preferences > Plugins > Marketplace > Search for "Debugger MCP Server" > Install

Using JetBrains Marketplace

Go to JetBrains Marketplace and install it by clicking the Install to ... button.

Manual Installation

Download the latest release and install it manually: Settings/Preferences > Plugins > ⚙️ > Install plugin from disk...

Quick Start

Install the plugin and restart your JetBrains IDE
Open a project - the MCP server starts automatically on an IDE-specific port
Find your IDE port: Settings > Tools > Debugger MCP Server (each IDE has a unique default port, e.g., 29190 for IntelliJ IDEA)
Configure your AI assistant with the server URL: http://127.0.0.1:{PORT}/debugger-mcp/streamable-http
Use the tool window (bottom panel: "Debugger MCP Server") to copy configuration or monitor commands

Using the "Install on Coding Agents" Button

The easiest way to configure your AI assistant:

Open the "Debugger MCP Server" tool window (bottom panel)
Click the prominent "Install on Coding Agents" button on the right side of the toolbar
A popup appears with three sections:
- Install Now - For Claude Code CLI and Codex CLI: Runs the installation command automatically
- Copy Configuration - For other clients (Gemini CLI, Cursor, etc.): Copies the JSON config to your clipboard
- Generic MCP Config - Streamable HTTP or Legacy SSE configuration for any MCP client
For "Copy Configuration" clients, paste the config into the appropriate config file

Example Workflow

Just tell your AI assistant:

"Debug the calculateTotal function—set a breakpoint at line 42, run the tests in debug mode, and show me the variable values when it pauses."

Or for more complex debugging:

"There's a bug in UserService. Set a breakpoint at line 42, run the tests in debug mode, and when it breaks, show me the stack trace and all local variables."

Client Configuration

Claude Code (CLI)

The easiest way is to use the "Install on Coding Agents" button in the IDE's tool window—it generates the correct command with your IDE-specific server name and port.

Or run this command manually in your terminal (replace <ide>-debugger and port with your IDE's values):

claude mcp add --transport http intellij-debugger http://127.0.0.1:29190/debugger-mcp/streamable-http --scope user

IDE-specific server names and default ports:

IDE	Server Name	Default Port
IntelliJ IDEA	`intellij-debugger`	29190
Android Studio	`android-studio-debugger`	29191
PyCharm	`pycharm-debugger`	29192
WebStorm	`webstorm-debugger`	29193
GoLand	`goland-debugger`	29194
PhpStorm	`phpstorm-debugger`	29195
RubyMine	`rubymine-debugger`	29196
CLion	`clion-debugger`	29197
RustRover	`rustrover-debugger`	29198
DataGrip	`datagrip-debugger`	29199
Aqua	`aqua-debugger`	29200
DataSpell	`dataspell-debugger`	29201
Rider	`rider-debugger`	29202

Options:

--scope user - Adds globally for all projects
--scope project - Adds to current project only

To remove: claude mcp remove intellij-debugger (use your IDE's name)

Codex CLI

The easiest way is to use the "Install on Coding Agents" button in the IDE's tool window—it generates the correct command with your IDE-specific server name and port.

Or run this command manually in your terminal (replace <ide>-debugger and port with your IDE's values):

codex mcp add intellij-debugger --url http://127.0.0.1:29190/debugger-mcp/streamable-http

To remove: codex mcp remove intellij-debugger (use your IDE's name)

Gemini CLI

Add to ~/.gemini/settings.json:

{
  "mcpServers": {
    "intellij-debugger": {
      "httpUrl": "http://127.0.0.1:29190/debugger-mcp/streamable-http"
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project root or ~/.cursor/mcp.json globally:

{
  "mcpServers": {
    "intellij-debugger": {
      "url": "http://127.0.0.1:29190/debugger-mcp/streamable-http"
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "intellij-debugger": {
      "serverUrl": "http://127.0.0.1:29190/debugger-mcp/streamable-http"
    }
  }
}

VS Code (Generic MCP)

{
  "mcp.servers": {
    "intellij-debugger": {
      "url": "http://127.0.0.1:29190/debugger-mcp/streamable-http"
    }
  }
}

Note: Replace intellij-debugger and the port with your IDE's server name and default port (see table above).

Note: The port can be changed in Settings > Tools > Debugger MCP Server.

Available Tools

The plugin provides 22 MCP tools organized by category:

Run Configuration Tools

Tool	Description
`list_run_configurations`	List all available run configurations in the project
`execute_run_configuration`	Execute a run configuration in debug or run mode

Debug Session Tools

Tool	Description
`list_debug_sessions`	List all active debug sessions with state and metadata
`start_debug_session`	Start a new debug session for a run configuration
`stop_debug_session`	Stop/terminate a debug session
`get_debug_session_status`	Get comprehensive status (variables, stack, source) in one call

Breakpoint Tools

Tool	Description
`list_breakpoints`	List all breakpoints with optional filtering
`set_breakpoint`	Set a line breakpoint with condition, log message, suspend policy
`remove_breakpoint`	Remove a breakpoint by ID or location

Execution Control Tools

Tool	Description
`resume_execution`	Resume paused execution
`pause_execution`	Pause running execution
`step_over`	Step over to next line (without entering methods)
`step_into`	Step into method calls
`step_out`	Step out of current method
`run_to_line`	Continue execution until a specific line

Stack & Thread Tools

Tool	Description
`get_stack_trace`	Get current call stack with file/line/method info
`select_stack_frame`	Change debugger context to a different stack frame
`list_threads`	List all threads with state information

Variable Tools

Tool	Description
`get_variables`	Get all variables visible in current stack frame
`set_variable`	Modify a variable's value during debugging

Navigation Tools

Tool	Description
`get_source_context`	Get source code around current execution point

Evaluation Tools

Tool	Description
`evaluate_expression`	Evaluate an expression or code fragment in debug context

Note: For detailed tool documentation with parameters, examples, and response formats, see USAGE.md.

Multi-Project Support

When multiple projects are open in a single IDE window, you must specify which project to use with the project_path parameter:

{
  "name": "set_breakpoint",
  "arguments": {
    "project_path": "/Users/dev/myproject",
    "file_path": "/Users/dev/myproject/src/Main.java",
    "line": 42
  }
}

If project_path is omitted:

Single project open: That project is used automatically
Multiple projects open: An error is returned with the list of available projects

Tool Window

The plugin adds a "Debugger MCP Server" tool window (bottom panel) that shows:

Server Status: Running indicator with server URL and port
Agent Rule Tip: Copy a rule for your AI agent's config to prefer debugger MCP tools
Project Name: Currently active project
Command History: Log of all MCP tool calls with:
- Timestamp
- Tool name
- Status (Success/Error/Pending)
- Parameters and results (expandable)
- Execution duration
Filters: Filter history by tool name, status, or search text

Tool Window Actions

Action	Description
Refresh	Refresh server status and command history
Copy URL	Copy the MCP server URL to clipboard
Clear History	Clear the command history
Export History	Export history to JSON file
Change Port	Open settings to configure server port and host
Star/Report Issues	Link to GitHub repository
Try IDE Index MCP Server	Link to companion plugin
Buy Me a Coffee	Support the developer
Get Companion Skill	Install or export the companion AI skill for enhanced debugging guidance
Install on Coding Agents	Install MCP server on AI assistants (prominent button on right)

Error Codes

JSON-RPC Standard Errors

Code	Name	Description
-32700	Parse Error	Failed to parse JSON-RPC request
-32600	Invalid Request	Invalid JSON-RPC request format
-32601	Method Not Found	Unknown method name
-32602	Invalid Params	Invalid or missing parameters
-32603	Internal Error	Unexpected internal error

Custom MCP Errors

Code	Name	Description
-32001	Session Not Found	Debug session not found
-32002	File Not Found	Specified file does not exist
-32003	Not Paused	Operation requires paused session
-32004	Breakpoint Error	Failed to set/remove breakpoint
-32005	Evaluation Error	Expression evaluation failed

Settings

Configure the plugin at Settings > Tools > Debugger MCP Server:

Setting	Default	Description
Server Host	127.0.0.1	Bind address for the MCP server. Use `127.0.0.1` for localhost only, `0.0.0.0` for all interfaces, or a custom IP
Server Port	IDE-specific	Each IDE has a unique default port (e.g., 29190 for IntelliJ, 29192 for PyCharm). Range: 1024-65535
Max History Size	1000	Maximum number of commands to keep in history

Requirements

JetBrains IDE 2025.1 or later (any IDE based on IntelliJ Platform)
JVM 21 or later
MCP Protocol 2025-03-26 (Streamable HTTP, primary) with 2024-11-05 (SSE, legacy) fallback

Supported IDEs

Fully tested: IntelliJ IDEA, PyCharm, WebStorm, GoLand, RustRover, Android Studio, PhpStorm May work (untested): RubyMine, CLion, DataGrip, Aqua, DataSpell, Rider

Architecture

The plugin runs an embedded Ktor CIO server on an IDE-specific port and supports three MCP transports:

Streamable HTTP Transport (Primary, MCP 2025-03-26)

AI Assistant ──────► POST /debugger-mcp/streamable-http   (JSON-RPC with Mcp-Session-Id header)
                     ◄── JSON-RPC response                (immediate HTTP response)
             ──────► DELETE /debugger-mcp/streamable-http  (session termination)

Legacy SSE Transport (MCP 2024-11-05)

AI Assistant ──────► GET /debugger-mcp/sse           (establish SSE stream)
                     ◄── event: endpoint             (receive POST URL with sessionId)
             ──────► POST /debugger-mcp?sessionId=x  (JSON-RPC requests)
                     ◄── HTTP 202 Accepted
                     ◄── event: message              (JSON-RPC response via SSE)

Stateless HTTP (Convenience)

AI Assistant ──────► POST /debugger-mcp              (JSON-RPC requests, no session)
                     ◄── JSON-RPC response           (immediate HTTP response)

This approach:

Modern clients - Streamable HTTP with session management per MCP 2025-03-26 spec
Legacy clients - Full SSE transport per MCP 2024-11-05 spec
Simple clients - Stateless HTTP for quick request/response without sessions
Each IDE gets a unique default port to avoid conflicts when multiple IDEs run simultaneously
Works with any MCP-compatible client
Supports CORS for browser-based clients

Contributing

Contributions are welcome! Please:

Fork the repository
Create a feature branch
Make your changes
Run tests: ./gradlew test
Submit a pull request

Development Setup

# Build the plugin
./gradlew build

# Run IDE with plugin installed
./gradlew runIde

# Run tests
./gradlew test

# Run plugin verification
./gradlew runPluginVerifier

License

This project is licensed under the MIT License - see the LICENSE file for details.

Plugin based on the IntelliJ Platform Plugin Template.

Name		Name	Last commit message	Last commit date
Latest commit History 92 Commits
.github		.github
.idea		.idea
.run		.run
gradle		gradle
src		src
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
LICENSE		LICENSE
README.md		README.md
USAGE.md		USAGE.md
build.gradle.kts		build.gradle.kts
codecov.yml		codecov.yml
gradle.properties		gradle.properties
gradlew		gradlew
gradlew.bat		gradlew.bat
qodana.yml		qodana.yml
settings.gradle.kts		settings.gradle.kts

Folders and files

Latest commit

History

Repository files navigation

Debugger MCP Server

Features

Why Use This Plugin?

Table of Contents

Installation

Using the IDE built-in plugin system

Using JetBrains Marketplace

Manual Installation

Quick Start

Using the "Install on Coding Agents" Button

Example Workflow

Client Configuration

Claude Code (CLI)

Codex CLI

Gemini CLI

Cursor

Windsurf

VS Code (Generic MCP)

Available Tools

Run Configuration Tools

Debug Session Tools

Breakpoint Tools

Execution Control Tools

Stack & Thread Tools

Variable Tools

Navigation Tools

Evaluation Tools

Multi-Project Support

Tool Window

Tool Window Actions

Error Codes

JSON-RPC Standard Errors

Custom MCP Errors

Settings

Requirements

Supported IDEs

Architecture

Streamable HTTP Transport (Primary, MCP 2025-03-26)

Legacy SSE Transport (MCP 2024-11-05)

Stateless HTTP (Convenience)

Contributing

Development Setup

License

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