MCP Go Debugger

A debugger interface for Go programs that integrates with MCP (Model Context Protocol).

Features

Launch and debug Go applications
Attach to existing Go processes
Set breakpoints
Step through code (step into, step over, step out)
Eval variables
View stack traces
List all variables in current scope
Get current execution position
Debug individual test functions with debug_test
Native integration with Delve debugger API types
Capture and display program output during debugging
Support for custom test flags when debugging tests
Detailed variable inspection with configurable depth

Installation

Prerequisites

Go 1.20 or higher

Using Go

The easiest way to install the MCP Go Debugger is with Go:

go install github.com/sunfmin/mcp-go-debugger/cmd/mcp-go-debugger@latest

This will download, compile, and install the binary to your $GOPATH/bin directory.

From Source

Alternatively, you can build from source:

git clone https://github.com/sunfmin/mcp-go-debugger.git
cd mcp-go-debugger
make install

Configuration

Cursor

Add the following to your Cursor configuration (~/.cursor/mcp.json):

{
  "mcpServers": {
    "go-debugger": {
      "command": "mcp-go-debugger",
      "args": []
    }
  }
}

Claude Desktop

Add the MCP to Claude Desktop:

claude mcp add go-debugger mcp-go-debugger

Verify the connection:

/mcp

Usage

This debugger is designed to be integrated with MCP-compatible clients. The tools provided include:

ping - Test connection to the debugger
status - Check debugger status and server uptime
launch - Launch a Go program with debugging
attach - Attach to a running Go process
debug - Debug a Go source file directly
debug_test - Debug a specific Go test function
set_breakpoint - Set a breakpoint at a specific file and line
list_breakpoints - List all current breakpoints
remove_breakpoint - Remove a breakpoint
continue - Continue execution until next breakpoint or program end
step - Step into the next function call
step_over - Step over the next function call
step_out - Step out of the current function
eval_variable - Eval a variable's value with configurable depth
list_scope_variables - List all variables in current scope (local, args, package)
get_execution_position - Get current execution position (file, line, function)
get_debugger_output - Retrieve captured stdout and stderr from the debugged program
close - Close the current debugging session

Basic Usage Examples

Debugging a Go Program

Ask the AI assistant to debug your Go program:

> Please debug my Go application main.go

The AI assistant will use the MCP to:

Launch the program with debugging enabled
Set breakpoints as needed
Eval variables and program state
Help diagnose issues

Attaching to a Running Process

If your Go application is already running, you can attach the debugger:

> Attach to my Go application running with PID 12345

Finding a Bug Example

> I'm getting a panic in my processOrders function when handling large orders. 
> Can you help me debug it?

The AI will help you:

Set breakpoints in the relevant function
Eval variables as execution proceeds
Identify the root cause of the issue

Debugging a Single Test

If you want to debug a specific test function instead of an entire application:

> Please debug the TestCalculateTotal function in my calculator_test.go file

The AI assistant will use the debug_test tool to:

Launch only the specific test with debugging enabled
Set breakpoints at key points in the test
Help you inspect variables as the test executes
Step through the test execution to identify issues
Eval assertion failures or unexpected behavior

You can also specify test flags:

> Debug the TestUserAuthentication test in auth_test.go with a timeout of 30 seconds

This is especially useful for:

Tests that are failing inconsistently
Complex tests with multiple assertions
Tests involving concurrency or timing issues
Understanding how a test interacts with your code

Inspecting Complex Data Structures

When working with nested structures or complex types:

> Can you eval the user.Profile.Preferences object at line 45? I need to see all nested fields in detail.

The AI will:

Set a breakpoint at the specified location
Use the eval_variable tool with appropriate depth parameters
Format the structure for easier understanding
Help navigate through nested fields

Debugging with Command Line Arguments

To debug a program that requires command-line arguments:

> Debug my data_processor.go with the arguments "--input=data.json --verbose --max-records=1000"

The debugger will:

Launch the program with the specified arguments
Allow you to set breakpoints and eval how the arguments affect execution
Help track how argument values flow through your program

Working with Goroutines

For debugging concurrent Go programs:

> I think I have a race condition in my worker pool implementation. Can you help me debug it?

The AI can:

Set strategic breakpoints around goroutine creation and synchronization points
Help eval channel states and mutex locks
Track goroutine execution to identify race conditions
Suggest solutions for concurrency issues

Stepping Through Function Calls

For understanding complex control flow:

> Walk me through what happens when the processPayment function is called with an invalid credit card

The AI assistant will:

Set breakpoints at the entry point
Use step-in/step-over commands strategically
Show you the execution path
Eval variables at key decision points
Explain the program flow

License

MIT License